WO2007075059A1

WO2007075059A1 - Digital broadcasting system and method of processing data

Info

Publication number: WO2007075059A1
Application number: PCT/KR2006/005807
Authority: WO
Inventors: Kyung Won Kang; In Hwan Choi; Kook Yeon Kwak
Original assignee: Lg Electronics Inc.
Priority date: 2005-12-28
Filing date: 2006-12-28
Publication date: 2007-07-05

Abstract

The present invention relates to a digital broadcasting system. More particularly, the present invention inserts and outputs pre-defined known data, which are already known by a transmitting system and a receiving system, in a specific place within a data area to which enhanced data are transmitted, and the receiving system uses the known data for a demodulating or equalizing process, thereby enhancing a receiving performance in an environment with frequent channel changes and vulnerable to noise. Also, the present invention performs non-systematic RS encoding on enhanced data including known data. Thereby the present invention may enable a continuously long known data sequence to be inserted and raise a degree of freedom for an insertion place.

Description

DIGITAL BROADCASTING SYSTEM AND METHOD OF

PROCESSING DATA

Technical Field

[1] The present invention relates to a digital telecommunication system, and more particularly, to an apparatus and a method that are used for transmitting and receiving digital broadcast programs. Background Art

[2] Presently, the technology for processing digital signals is being developed at a vast rate, and, as a larger number of the population uses the Internet, digital electric appliances, computers, and the Internet are being integrated. Therefore, in order to meet with the various requirements of the users, a system that can transmit diverse supplemental information in addition to video/audio data through a digital television channel needs to be developed.

[3] Some users may assume that supplemental data broadcasting would be applied by using a PC card or a portable device having a simple in-door antenna attached thereto. However, when used indoors, the intensity of the signals may decrease due to a blockage caused by the walls or disturbance caused by approaching or proximate mobile objects. Accordingly, the quality of the received digital signals may be deteriorated due to a ghost effect and noise caused by reflected waves. However, unlike the general video/audio data, when transmitting the supplemental data, the data that is to be transmitted should have a low error ratio. More specifically, in case of the video/ audio data, errors that are not perceived or acknowledged through the eyes or ears of the user can be ignored, since they do not cause any or much trouble. Conversely, in case of the supplemental data {e.g., program execution file, stock information, etc.), an error even in a single bit may cause a serious problem. Therefore, a system highly resistant to ghost effects and noise is required to be developed.

[4] The supplemental data are generally transmitted by a time-division method through the same channel as the video/audio data. However, with the advent of digital broadcasting, digital television receivers that receive only video/audio data are already supplied to the market. Therefore, the supplemental data that are transmitted through the same channel as the video/audio data should not influence the conventional receivers that are provided in the market. In other words, this may be defined as the compatibility of broadcast system, and the supplemental data broadcast system should be compatible with the broadcast system. Herein, the supplemental data may also be referred to as enhanced data. Furthermore, in a poor channel environment, the receiving performance of the conventional receiver may be deteriorated. More specifically, resistance to changes in channels and noise is more highly required when using portable and/or mobile receivers. Disclosure of Invention

Technical Problem

[5] Accordingly, the present invention is to provide a digital broadcasting system that is suitable for transmitting supplemental data and that is highly resistant to noise.

[6] The present invention is to provide a broadcasting system and a method of processing data that can periodically insert known data in a specific domain of the supplemental data and transmitting the data to a broadcast receiving system, thereby enhancing the receiving performance of the broadcast receiving system.

[7] The present invention is to provide a system for a digital broadcast and method of processing the same, by which known data insertion is efficiently facilitated in a manner of performing non-systematic RS encoding on enhanced data including known data. Technical Solution

[8] To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a method of processing a digital broadcast according to the present invention includes grouping a plurality of consecutive enhanced data packets and determining a place of a known data sequence within the group to enable a sequence of known data to be inserted and outputted with a uniform interval in a symbol area after data interleaving, determining a known data place for memory initialization of a Trellis encoder at a beginning part of the known data sequence with reference to a data output sequence after the data interleaving, if the place of the known data is determined, determining a non-systematic RS parity place to be transmitted behind the known data for the initialization in the data output sequence after the data interleaving, and performing non-systematic RS encoding on the enhanced data packet.

[9] The interval for inserting the known data sequence within the group is an integer multiplication of a data segment length in the symbol area after the data interleaving.

[10] The known data sequence inserted with the uniform interval is identical to each other.

[11] If a segment sync symbol is inserted in a middle part of the known data symbol sequence inserted with the uniform interval, the segment sync symbol is always inserted in a constant place.

[12] In another aspect of the present invention, a method of processing a digital broadcast includes grouping a plurality of consecutive enhanced data packets, each comprising at least one of enhanced data and known data, determining a place of a data sequence within the group to enable a sequence of known data to be inserted and outputted with a uniform interval in a symbol area after data interleaving, performing the data interleaving on an inputted enhanced data packet after inserting a plurality of non-systematic RS parities or RS parity place holders in the inputted enhanced data packet, performing memory initialization and Trellis encoding on the outputted data to output, if data interleaved and outputted is the known data and corresponds to a first part of a consecutive known data sequence, and calculating non-systematic RS parity using data within the enhanced data packet prior to the data interleaving and data for the memory initialization and then performing Trellis encoding by substituting the non-systematic RS parity or the RS parity place holder.

[13] In another aspect of the present invention, a transmitting system includes an packet formatter and multiplexer, an post-processor, a non-systematic RS parity place holder inserter and data interleaver.

[14] The packet formatter and multiplexer may group a plurality of consecutive enhanced data packets, each comprising at least one of enhanced data and known data, the packet formatter and multiplexer may determine a place of a data sequence within the group to enable a sequence of known data to be inserted and outputted with a uniform interval in a symbol area after data interleaving, the packet formatter and multiplexer may multiplex the enhanced data packet group with a main data packet. The post-processor may perform data interleaving on an output of the packet formatter and multiplexer after inserting a plurality of RS parity place holders in the output of the packet formatter and multiplexer, the post-processor may perform additional encoding only if the interleaved data is the enhanced data, the post-processor may perform data deinterleaving and RS parity place holder removal. The non- systematic RS parity place holder inserter and data interleaver may perform data interleaving on an output of the post-processor by inserting a plurality of non-systematic RS parities or RS parity place holders in the output of the post-processor, the non-systematic RS parity place holder inserter and data interleaver may output the interleaved data for Trellis encoding.

[15] In another aspect of the present invention, a receiving system includes a demodulator and equalizer receiving a signal transmitted from a digital transmitting system by tuning, the demodulator and equalizer performing demodulation and channel equalization by applying known data to the received signal, a known data detector and generator detecting the known data inserted by a transmitting side from the signal prior to the demodulation or the demodulated signal, the known data detector and generator outputting the detected known data to the demodulator and equalizer, and a non-systematic RS parity remover removing non-systematic RS parity byte inserted in a received packet if the received packet is an enhanced data packet. [16] It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. Advantageous Effects

[17] The present invention provides the following effects or advantages.

[18] The present invention is strong against error in transmitting additional data via a channel. And, the present invention is compatible with a conventional receiver. Moreover, the present invention enables an errorless reception of additional data on a channel having ghost and noise worse than those of the related art receiving system.

[19] The present invention also transmits known data inserted in a specific place of a data area, thereby enhancing reception performance of a receiving system having considerable channel variations.

[20] In particular, the present invention can move a parity place by performing non- systematic RS encoding on enhanced data packet including known data, thereby inserting a consecutively long known data sequence and raising a degree of freedom of an insertion place. In particular, it is possible to insert known data in a parity area of systematic RS encoding and to expand an area where initialization bytes can be inserted.

[21] Accordingly, the present invention is effectively applicable to a portable or mobile receiving system requiring robustness against noise with considerable channel variations. Brief Description of the Drawings

[22] FIG. 1 is a block diagram of a digital broadcast transmitting system according to one embodiment of the present invention;

[23] FIG. 2 is a block diagram of a Trellis encoding unit of the digital broadcast transmitting system shown in FIG. 1 ;

[24] FIG. 3 is a diagram of a data interleaver shown in FIG. 2;

[25] FIG. 4 is a diagram for explaining an output sequence of a data interleaver on a transmitted frame;

[26] FIG. 5 is diagram of data configurations of front and rear ends of a data interleaver according to known data insertion of the present invention;

[27] FIGs. 7 to 9 are diagrams of data configurations in byte and symbol areas of front and rear ends of a data interleaver according to the present invention, in which known data are inserted by 4-data segment cycle;

[28] FIGs. 10 to 12 are diagrams of data configurations in byte and symbol areas of front and rear ends of a data interleaver according to the present invention, in which known data are inserted by 5-data segment cycle;

[29] FIGs. 13 to 15 are diagrams of data configurations in byte and symbol areas of front and rear ends of a data interleaver according to the present invention, in which known data are inserted by 8-data segment cycle;

[30] FIG. 16 is a block diagram of a digital broadcast receiving system according to one embodiment of the present invention;

[31] FIG. 17 illustrates a block diagram of a digital broadcast (or television or DTV) transmitting system according to another embodiment of the present invention;

[32] FIG. 18 illustrates a block diagram showing a general structure of a demodulating unit within a digital broadcast (or television or DTV) receiving system according to another embodiment of the present invention;

[33] FIG. 19 illustrates a block diagram showing the structure of a digital broadcast (or television or DTV) receiving system according to an embodiment of the present invention; and

[34] FIG. 20 illustrates a block diagram showing the structure of a digital broadcast (or television or DTV) receiving system according to another embodiment of the present invention. Best Mode for Carrying Out the Invention

[35] Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[36] In addition, although the terms used in the present invention are selected from generally known and used terms, some of the terms mentioned in the description of the present invention have been selected by the applicant at his or her discretion, the detailed meanings of which are described in relevant parts of the description herein. Furthermore, it is required that the present invention is understood, not simply by the actual terms used but by the meaning of each term lying within.

[37] In the present invention, the enhanced data may either consist of data including information such as program execution files, stock information, and so on, or consist of video/audio data. Additionally, the known data refer to data already known based upon a pre-determined agreement between the transmitting system and the receiving system. Furthermore, the main data consist of data that can be received from the conventional receiving system, wherein the main data include video/audio data.

[38] The present invention enhances reception performance of a receiving system in a manner of multiplexing enhanced data and known data known by a transmitting/ receiving side and transmitting the multiplexed data. [39] In particular, by performing non-systematic RS encoding on enhanced data including known data, the present invention enables a continuously long known data sequence to be inserted and raises a degree of freedom for an insertion place.

[40] FIG. 1 is a block diagram of a digital broadcast transmitting system according to one embodiment of the present invention.

[41] Referring to FIG. 1, a digital broadcast transmitting system according to one embodiment of the present invention includes a pre-processor 101, a packet formatter 102, a packet multiplexer 103, a data randomizer 104, a scheduler 105, a postprocessor 110, an RS (Read-Solomon) encoder & non-systematic RS parity holder inserter 121, a data interleaver 122, a trellis encoding unit 123, a backward-compatibility processor 130, a frame multiplexer 140 and a transmitting unit 150.

[42] In the above-configured transmitting system, main data is outputted to the packet multiplexer 103 by transport packet unit, whereas enhanced data is outputted to the pre-processor 101.

[43] The pre-processor 101 performs pre-processing such as additional error correction encoding, interleaving, null data insertion and the like on the enhanced data and then outputs the pre-processed data to the packet formatter 102.

[44] The packet formatter 102 configures a group by multiplexing the pre-processed enhanced data and previously defined known data or a known data place holder together under the control of the scheduler 105. The packet formatter 102 divides data within the group into 184-byte enhanced data packets, attaches a 4-byte MPEG header to a front of each of the packets and then outputs a 188-byte enhanced data packet (i.e., MPEG compatible packet). In particular, one enhanced data packet group includes a plurality of consecutive enhanced data packets. An insertion place of the known data will be explained in detail later.

[45] An output of the packet formatter 102 is inputted to the packet multiplexer 103. The packet multiplexer 103 performs time division multiplexing on the 188-byte main data packet and the 188-byte enhanced data packet by transport stream (TS) packet unit to output under the control of the scheduler 105.

[46] In particular, the scheduler 105 generates a control signal enabling the packet multiplexer 103 to multiplex the main and enhanced data packets together and then outputs the control signal to the packet multiplexer 103. If so, the packet multiplexer 103 having received the control signal multiplexes the main data packet and the enhanced data packet into the TS packet unit to output.

[47] An output of the packet multiplexer 103 is inputted to the data randomizer 104. The data randomizer 104 removes MPEG sync byte from an input packet, randomizes the rest 187 bytes using an internally generated pseudo-random byte and then outputs the randomized packet to the post-processor 110. [48] The post processor 110 includes an RS encoder & non-systematic parity place holder inserter 111, a data interleaver 112, an convolutional coder 113, a data in- terleaver 114 and an RS byte remover 115.

[49] The RS encoder & non-systematic parity place holder inserter 111 of the postprocessor 110 performs systematic RS encoding or non-systematic parity place holder insertion on the randomized data.

[50] In particular, if a 187-byte packet outputted from the data randomizer 104 is a main data packet, the RS encoder & non-systematic parity place holder inserter 111 attaches a 20-byte parity byte to a rear of the 187-byte data by performing systematic RX encoding like the conventional broadcast system and then outputs the attached data to the data interleaver 112.

[51] Meanwhile, if a 187-byte packet outputted from the data randomizer 104 is an enhanced data packet, the RS encoder & non-systematic parity place holder inserter 111 determines a 20-parity byte place within the packet, inserts a null byte in the determined parity byte place, sequentially inserts bytes of the enhanced data packet in the rest of 187 byte places and then outputs them to the data interleaver 112.

[52] In this case, the place of the RS parity byte corresponds to a parity place in a non- systematic RS encoder and may differ for each enhanced data packet. This is because a place where known data (or known data place holder) is inserted can differ for each enhanced data packet. And, a known data place holder to initialize a memory of a trellis encoder can be inserted. If the known data place holder is inserted, its place may differ.

[53] In this case, the place of the RS parity byte should be placed in a manner that the

RS parity place holder bytes are outputted behind the known data for initialization (or known data place holder for initialization) at the data interleaver.

[54] In particular, the position of the known data (or known data place holder) used in initializing the trellis encoder should be determined to be outputted ahead of the RS parity byte place from the data interleaver output end.

[55] In other words, the known data (or known data place holder) used in initializing the trellis encoder needs to be outputted earlier than the RS parity place holder at the output end of the data interleaver. Yet, the rest of the known data (or known data place holder) unused in initializing the trellis encoder can be outputted behind or ahead of the RS parity place holder.

[56] The data interleaver 112 performs data interleaving on an output of the RS encoder

& non-systematic parity place holder inserter 111 and then outputs it to the convolutional coder 113. A data interleaving operation of the data interleaver 112 will be explained in detail later.

[57] The convolutional coder 113 performs convolutional coding on an output of the data interleaver 112 and then outputs it to the data deinterleaver 114.

[58] The data deinterleaver 114 performs data deinterleaving on input data by a reverse process of the data interleaver 112 and then outputs the deinterleaved data to the RS byte remover 115.

[59] The RS byte remover 115 removes the 20-byte parity attached by the RS encoder & non-systematic parity place holder inserter 111. In this case, if the inputted data is the main data packet, the RS byte remover removes last 20 bytes from 207 bytes. IF the inputted data is the enhanced data packet, the RS byte remover 115 removes 20-byte RS parity place holder from 207 bytes. This is to re-calculate parities since original data is modified by the convolutional coder 113 in case of the enhanced data.

[60] The convolutional coder 113 converts inputted bytes to symbols, performs convolutional coding on an enhanced data symbol only, converts the coded result to bytes, and then outputs the converted bytes. In particular, the convolutional coder 113 outputs data without modification if an output of the data interleaver 112 is the main data, the MPEG header byte attached by the packet formatter 102 or the RS parity byte or parity place holder byte attached to the enhanced data packet by the RS encoder & non- systematic RS parity place holder inserter 111.

[61] Meanwhile, the known data can be inserted in the enhanced data packet by the packet formatter 102. Alternatively, the packet formatter 102 inserts a place holder of the known data and the convolutional coder 113 inserts the known data in the corresponding place instead of the place holder. And, the convolutional coder 113 outputs the known data symbol without additional coding like the main data.

[62] An output of the RS byte remover 115 is inputted to the RS encoder & non- systematic RS parity place holder inserter 121.

[63] Like the former RS encoder & non-systematic RS parity place holder inserter 111, if a 187-byte packet outputted from the RS byte remover 115 is a main data packet, the RS encoder & non-systematic RS parity place holder inserter 121 attaches 20-byte parity bytes to a rear of 187-byte data by performing systematic RS encoding in the same manner of the conventional broadcast system. In case of an enhanced data packet, a 20-parity byte place is determined and it is able to insert RS parity obtained by performing non- systematic RS encoding in the determined parity byte place or to insert null byte (i.e., RS parity place holder) therein instead of the RS parity. And, bytes within the enhanced data packet are sequentially inserted in the rest 187 byte places among 207 byte places. The null byte can be set to an arbitrary value and is replaced by a parity value calculated by a non-systematic RS encoder 133 of the backward-compatibility processor 130. Hence, the null byte plays a role in holding a place of the parity byte of a non- systematic RS code.

[64] An output of the RS encoder and non- systematic RS parity place holder inserter 121 is outputted to the data interleaver 122 and also inputted to a backward-compatibility processor 130 to re-calculate parity in case of the enhanced data packet.

[65] Besides, the data interleaver 122 performs interleaving on input data according to the same interleaving rule of the former data interleaver 112.

[66] FIG. 3 is a diagram of the data interleaver (122 or 112) shown in FIG. 2, in which a convolutional interleaver is exemplarily shown. In this case, the number of branches is 52 and the number (M) of unit memory bytes is 4 (M = 4).

[67] Referring to FIG. 3, in the data interleaver, if a first byte is inputted, it is directly outputted via a first branch. A second byte is inputted via a second branch, by which a value prior to 52*4 byte is outputted.

[68] FIG. 4 is a diagram for explaining input and output sequences of a data interleaver on a transmitted frame.

[69] Referring to FIG. 4, data inputs are sequentially inputted by segment unit from top to bottom. And, bytes within a segment are sequentially inputted left to right. Numerals in the drawing indicate output sequences of a data interleaver. In this case, the data interleaver operates by 52-segment unit.

[70] An output of the data interleaver 122 is inputted to the trellis encoding unit 123.

And, the trellis encoding unit 123 encodes a 2-bit input into three bits to output.

[71] An output of the trellis encoding unit 123 is inputted to the frame multiplexer 140.

[72] The frame multiplexer 140 inserts a field sync and a segment sync in the output of the trellis encoding unit 123 and then outputs a corresponding signal to the transmitting unit 150.

[73] The transmitting unit 150 includes a pilot inserter 151, a modulator 152 and a radio frequency (RF) converter 153. And, the transmitting unit 150 plays the same role of the conventional transmitter.

[74] To make the output data of the trellis encoding unit 123 into known data defined by a transmitting/receiving side, initialization of a memory within the trellis encoding unit 123 is needed for the known data inserted in the enhanced data packet.

[75] For the initialization, an input of the trellis encoder needs to be modified. And, RS parity affected by the correspondingly modified data is re-calculated to be substituted for original parity data. This process is performed by the backward-compatibility processor 130.

[76] FIG. 2 is a detailed diagram of the trellis encoding unit 123 that can be initialized.

[77] Referring to FIG. 2, a trellis encoding unit according to one embodiment of the present invention includes a byte-to-symbol converter 201, a multiplexer 202 selecting a trellis encoder input, a trellis encoder 203 and an initialization controller 204 initializing the trellis encoder.

[78] The byte-to-symbol converter 201 of the trellis encoder unit receives data-in- terleaved data by byte unit, converts the received data to symbol unit, performs 12- way interleaving, and then outputs the interleaved data to the multiplexer 202.

[79] In general, an output of the byte-to-symbol converter 201 is selected by the multiplexer 202 and is then directly outputted to the trellis encoder 203. Yet, if the interleaved data is known data and if the known data corresponds to a beginning part of a known data sequence consecutively inputted, initialization of the trellis encoder 203 is necessary. The trellis encoder 203 includes a memory and a current output is affected by a current and previous inputs. So, in order to output a known data pattern after trellis encoding, a process for initializing the memory within the trellis encoder 203 to a predetermined value is needed.

[80] In case that the initialization of the memory of the trellis encoder 203 is needed, a portion of the known data is replaced by initialization data to be outputted to the trellis encoder 203. If so, the memory within the trellis encoder 203 is initialized to a predetermined value by the initialization data. An output of the trellis encoder 203 after the initialization can become the known data encoded into a pattern promised by the transmitting/receiving side.

[81] The initialization controller 204 initializing the trellis encoder 203 receives a value of the memory within the trellis encoder 203, generates initialization data to be inputted to the trellis encoder 203, and then outputs the generated data to the multiplexer 202 and the backward-compatibility processor 130.

[82] In particular, the trellis encoder 203 encodes an upper bit of two bits configuring one symbol into 1 bit using one memory and then outputs the 1 bit. And, the trellis encoder 203 encodes a lower bit of the two bits into 2 bits using two memories and then outputs the 2 bits. In this case, if input data is the known data and if the known data corresponds to a beginning part of a consecutively inputted known data sequence, the memories need to be initialized to output specific known data after trellis encoding.

[83] So, if the initialization of the memory within the trellis encoder 203 is needed, the initialization controller 204 generates initialization data according to a current state and specific initialization state of the memory and then outputs the generated initialization data to the multiplexer 202.

[84] The initialization data consists of 4 bits, i.e., two symbols. In this case, the trellis encoder 203 includes twelve encoders. And, twelve bytes outputted from the multiplexer 202 are sequentially inputted to the twelve encoders, respectively. In this case, initial four bits, i.e., two symbols of each byte can become the initialization data. In particular, the initialization controller 204 generates initialization data for initializing the memory of the trellis encoder 203 in the two symbol sections from which a known data sequence starts and then outputs the generated initialization data to the multiplexer 202 and the backward-compatibility processor 130. [85] The backward-compatibility processor 130 receives the output of the RS encoder & non-systematic parity place holder inserter 121 and the output of the initialization controller 204 of the trellis encoding unit 123, generates non-systematic 20-byte parity and then outputs the generated parity to the multiplexer 202 of the trellis encoding unit 123.

[86] In particular, since the initialization for the memory of the trellis encoding unit 123 is achieved by new data instead of being achieved by the data interleaved by the data interleaver 122, the RS parity is re-generated to be substituted for original parity data. And, this is performed by the backward-compatibility processor 130.

[87] The backward-compatibility processor 130 includes a packet buffer 131, a symbol- to-byte converter 132, a non- systematic RS encoder 133 and a byte-to-symbol converter 134.

[88] The output of the RS encoder & non-systematic RS parity place holder inserter 121 is inputted to the data interleaver 122 and the packet buffer 131 of the backward- compatibility processor 130. And, the initialization data of the initialization controller 204 of the trellis encoding unit 123 is inputted to the multiplexer 202 of the trellis encoding unit 123 and the symbol-to-byte converter 132 of the backward-compatibility processor 130.

[89] In this case, since the input and output of the RS encoder and non-systematic RS parity place holder inserter 121 follow byte units, the symbol-to-byte converter 132 converts the symbol unit of the initialization data to the byte unit and then outputs the converted data to the packet buffer 131.

[90] The packet buffer 131 receives a byte output of the RS encoder and non-systematic

RS parity place holder inserter 121 and a byte output of the symbol-to-byte converter 132, temporarily stores the received outputs and then outputs the stored outputs to the non-systematic RS encoder 133.

[91] The non- systematic RS encoder 133 receives a byte output of the packet buffer 131, generates 20-byte parity and then outputs the generated parity to the multiplexer 202 of the trellis encoder 13 via the byte-to-symbol converter 134 for the unit conversion to the symbol unit.

[92] If the inputted data, which was interleaved and converted to the symbol, corresponds to the beginning part of the known data sequence, the multiplexer 202 selects to output an initialization symbol of the initialization controller 204 instead of the inputted symbol. If the inputted data is a parity place holder, the multiplexer 202 selects an output symbol of the symbol-to-byte converter 134 of the backward- compatibility processor 130 instead of the inputted symbol. In other cases, the multiplexer 202 selects the inputted data from the byte-symbol converter 201, which was interleaved and converted to the symbol, and then outputs the selected data to the trellis encoder 203.

[93] In particular, symbols at the first two places of the known data sequence are substituted by the initialization symbols to be inputted to the trellis encoder 203. A symbol at a parity place within each packet is substituted by the parity symbol recalculated by the backward-compatibility processor 130 to be inputted to the trellis encoder 203. In case that the RS encoder & non-systematic RS parity place holder inserter 121 inserts a null byte for the enhanced data packet instead of inserting a non- systematic RS parity, a non- systematic RS parity of the enhanced data packet is calculated by the backward-compatibility processor 130 regardless of the initialization of the trellis encoder to be substituted for the null byte and is then inputted to the trellis encoder 203.

[94] The trellis encoder 203 performs trellis encoding on the data outputted from the multiplexer 202 and then outputs the encoded data to the frame multiplexer 140. And, the trellis encoder 203 outputs a state of the memory within the trellis encoder to the initialization controller 204.

[95] Known Data Insertion and Non-systematic RS Parity Place

[96] Known data insertion and non- systematic RS parity place Setting according to the present invention are explained in detail as follows.

[97] First of all, if an inputted 187-byte packet is a main data packet, the RS encoder & non-systematic RS parity place holder inserter generates 20-byte parity by performing systematic RS encoding like the broadcast system and then attaches the generated 20-byte parity to a rear of the 187-byte.

[98] In case of an enhanced data packet, 187 bytes among 207 bytes to be outputted correspond to the inputted data and 20 bytes become a parity byte. This is the same case of the systematic RS encoding. Yet, a place of the 20-byte parity may differ within 207 bytes for each enhanced data packet and a parity value is found by non- systematic RS encoding.

[99] Once the parity place is determined, data is placed at 187 bytes where the parity is not located.

[100] Non-systematic parities inserted by the RS encoder & non- systematic RS parity place holder inserter may become practical parties or just correspond to a meaningless byte for holding the parity place. In case that the non-systematic RS parities are inserted as the meaningless byte, the backward-compatibility processor calculates the parity value for substitution.

[101] The RS parity is re-calculated by the backward-compatibility processor for the enhanced data packet including the trellis initialization data, of which reason is explained as follows.

[102] For an enhanced data packet that includes a known data to be replaced by the trellis initialization data, it is required to re-calculate the RS parity data for the enhanced data packet since the replacement by the initialization data is performed in the trellis encoding unit 123 which is behind the RS encoder or non-systematic RS parity place holder inserter 121.

[103] In other words, if a place of a parity existing within one packet comes behind the data to be substituted by initialization at an input of the trellis encoder, it is able to calculate a new parity by RS encoding by using the substituted data. In this case, if systematic RS encoding is performed on the enhanced data packet including the initialization data, it is unable to insert known data in a parity area since the RS parity place is already determined. And, a place of data coming ahead of the parity is very limited. So, an area available for trellis initialization is correspondingly limited.

[104] Yet, if the non-systematic RS encoding is performed on the enhanced data packet including the initialization data, the parity place is movable and the known data can be inserted in the parity area of the systematic RS encoding. And, it is also advantageous that the limitation of the data place for the trellis initialization is almost eliminated as compared with the case of using the systematic RS encoder.

[105] Yet, the known data (or known data place holder) used for the initialization of the trellis encoder should be inputted to the trellis encoding unit 123 ahead of the RS parity place holder.

[106] If one packet is inputted to the data interleaver shown in FIG. 3, it is interleaved and outputted by byte unit. The interleaving does re-ordering of data sequence.

[107] FIG. 4 is a diagram for explaining input/output order of a data interleaver on a VS frame.

[108] Referring to FIG. 4, data within a packet is inputted to the data interleaver by byte unit. In this case, the data is inputted top to bottom according to a segment sequence. And, the data in inputted from a left first byte to a right 207^th byte in order within a segment.

[109] Thus, if the data is inputted and if an n^Λ field starts in FIG. 4, a data interleaver input is carried out in a sequence of byte #1, byte #210 and the like. And, a data interleaver output is carried out in a sequence of byte #1, byte #2, byte #3 and the like. Hence, the sequence of the inputted bytes and the sequence of the outputted bytes are different from each other by interleaving.

[110] In particular, since the data interleaver has the configuration of the convolutional interleaver having the branch (B) of 52, the sequence, as shown in FIG. 4, goes round by a 52-byte cycle in outputting one segment. Hence, byte #210, byte #262 and the like are outputted after byte #1, byte #53, byte #105 and byte #157 have been outputted.

[I l l] So, if the systematic RS encoding is to be performed, RS parity should exist at last

20 bytes of each segment. And, RS parities can be outputted according to the in- terleaved output sequence ahead of the initialization bytes for the trellis initialization for the known data generation.

[112] If so, RS encoding should be performed ahead of information indicating how data should be substituted for the initialization. Yet, this is impossible. So, error takes place in RS decoding.

[113] In aspect of one segment unit for the data interleaver output, each segment can be configured in a manner that substitution data for initialization is located at a place of data outputted ahead of all systematic RS parity bytes. Yet, places of initialization bytes are restricted to limited area, and thus this to put limitation on an area in which known data can be inserted.

[114] Yet, as mentioned in the foregoing description, in aspect of a place of RS parity within one segment and in aspect of an output of the data interleaver, the restriction, which occurs in case of using the systematic RS encoding only, for the known data insertion place can be eliminated only if parity is calculated by enabling the RS parity to be outputted behind the initialization bytes and by performing the non-systematic RS encoding. And, compatibility with the conventional receiver incapable of supporting E-VSB can be maintained as well.

[115] FIG. 5 is diagram of data configurations before and after a data interleaver according to known data insertion of the present invention.

[116] In FIG. 5, a data configuration at an input end of a data interleaver is shown. And, a configuration at an output end of the data interleaver corresponding to the input configuration of FIG. 5 is shown in FIG. 6.

[117] First of all, a receiving system receives data in an order of a data interleaver output end. To receive consecutive known data, known data should be consecutively inserted like the numbering sequence of FIG. 4.

[118] In order to make one segment received by the receiving system into the known data like the example shown in FIG. 6, one segment is divided into 52 bytes unit and the known data should be inserted in the same byte position by 52-byte unit like the example shown in FIG. 5. In this case, an initialization byte needs to be placed at a beginning part of a known data sequence. Hence, once a place of the known data within the segment is determined, a place, where normal data ends and the known data begins in aspect of a data interleaver output end, is determined as the place of the initialization byte.

[119] Once the places of the known data and the initialization byte are determined, it is able to determine a place of a non-systematic RS parity byte. In this case, parity bytes are placed to be outputted behind the initialization bytes in aspect of the data interleaver output. In particular, in aspect of one segment, since a sequence having a small numbering in FIG. 4 is firstly outputted from the data interleaver, the RS parity is placed to a number behind the sequence numbers of the initialization bytes.

[120] For example of inserting the known data, in aspect of a data interleaver output configuration shown in FIG. 6, if known data is inserted behind MPEG header in a first segment to reach the end of the segment, the MPEG header bytes in the second segment can be used a continuation of the known data because the MPEG header bytes for an enhanced data packet have a pre-determined value between a transmitting system and a receiving system.

[121] FIGs. 7 to 9 show configurations of enhanced data packet groups according to the known data insertion of the present invention, respectively.

[122] FIG. 7 shows a data configuration at an input end of the data interleaver 112 or 122 and FIG. 8 shows a data configuration at an output end of the data interleaver 112 or 122. And, FIG. 9 shows a data configuration result of output bytes of the data interleaver, in which the output bytes are converted to symbols by the trellis encoding unit 123 and are interleaved in a symbol domain.

[123] In FIG. 7, a small rectangle means one byte, one row means one enhanced data packet including 207 bytes, and 104 consecutive enhanced data packets configure one group. In the drawing, a 3-byte MPEG transport header byte excluded 0x47 sync byte is inserted by the packet formatter 102, a known data place holder byte inserted by the packet formatter 102, a 304 area indicates a non-systematic RS parity place holder or RS parity inserted by the RS encoder & non-systematic RS parity place holder inserter 111 or 121, a 305 area indicates enhanced data, and a 302 area indicates a known data place holder byte to be used in initializing the trellis encoder.

[124] Meanwhile, in the drawing, a 306 or 307 area indicates enhanced data. The enhanced data in the 306 area is interleaved with main data prior to an enhanced data packet group by the data interleaver 112 or 122 and is then outputted. The enhanced data in the 307 area is interleaved with main data after the enhanced data packet group by the data interleaver 112 or 122 and is then outputted.

[125] If the enhanced data packet group shown in FIG. 7 is interleaved by the data interleaver 112 or 122, it is outputted as shown in FIG. 8.

[126] In FIG. 8, a white area indicates main data bytes before and after the enhanced data packet group. And, FIG. 8 shows that bytes of the enhanced data packet group are mixed with the main data bytes. The enhanced data packet group according to the present invention, as shown in FIG. 8, is characterized in that a sequence of known data is periodically outputted from the output end of the data interleaver 112 or 122.

[127] Meanwhile, FIG. 9 shows a data output of an area corresponding to middle 52 packets in FIG. 8. In this case, the area is converted to symbols from bytes by the trellis encoding unit 123, encoded and then goes through the frame multiplexer 140. In particular, FIG. 9 shows a data configuration in a symbol domain. [128] One small rectangle in FIG. 9 means one symbol and one row indicates one data segment configured with 4 segment sync symbols and 828 (= 207 x 4) data symbols.

[129] An output of the data interleaver 122 is converted to symbol from byte via the trellis encoding unit 123, interleaved and trellis -encoded in a symbol domain and is then inputted to the frame multiplexer 140.

[130] The frame multiplexer 140 attaches four segment sync symbols to each trellis- encoded input 828 symbols to configure a data segment having 832 symbols. In FIG. 9, a 308 area indicates segment sync symbols inserted by the frame multiplexer 140.

[131] A 12-byte 308 area in front of each known data sequence repeated each four segments in FIG. 8 indicates a byte to be used in initializing twelve trellis encoders and is converted to 48 symbols by the trellis encoding unit 123 to have the configuration shown in FIG. 9. Since two symbols are needed to initialize each of the trellis encoders and since there are total twelve trellis encoders, total 24 symbols are used for the trellis initialization among the 48 symbols in a manner of assigning two initial symbols to each of the trellis encoders. So, the rest 24 symbols can be used as known data symbols.

[132] Meanwhile, an area enclosed by a black rim is an area in which a same known data symbol sequence is repetitively inserted with uniform interval. In this case, the interval for inserting the known data symbol sequence preferably corresponds to an integer multiplication of a data segment length. This is to enable a segment sync symbol inserted by the frame multiplexer 140 to be inserted in the same position within the known data sequence so that the segment sync symbol is used as a portion of the known data sequence.

[133] Although FIGs. 7 to 9 show the embodiments of configuring one group with 104 enhanced data packets, the number of enhanced packets configuring one group can be arbitrarily chosen. Yet, since the data interleaver 112 or 122 interleaves data by 52-packet unit, the number is preferably chosen to be an integer multiple of 52 packets.

[134] In FIG. 9, the known data symbol sequence is repetitively inserted with 4-segment interval. FIGs. 10 to 12 show a case that the known data symbol sequence is repetitively inserted with 5 -segment interval. FIGs. 13 to 15 show a case that the known data symbol sequence is repetitively inserted with 8-segment interval.

[135] Thus, the enhanced data packet according to the present invention can be configured to include the enhanced data carrying information and the known data inserted for reception performance enhancement.

[136] In this case, it is needed to initialize one or more memories of a trellis encoder at a beginning part of a known data sequence with reference to an output sequence of the data interleaver. If the initialization byte is located within a data segment, non- systematic RS parity bytes should be placed to be outputted behind the initialization byte in an output sequence of the data interleaver. Namely, if there is no initialization byte in the data segment, a place of the non-systematic RS parity byte can be randomly chosen.

[137] By considering the relation between the position of the known data place holder for initializing the trellis encoder and the position of the non-systematic RS parity byte, the enhance data packet is configured in a manner that the packet formatter 102 determines the known data place and that the RS parity place holder inserter 111 or 121 inserts the non-systematic RS parity place holder.

[138] FIG. 16 is a block diagram of a demodulating unit including a digital broadcast receiving system according to one embodiment of the present invention. In particular, the demodulating unit receives data transmitted from the digital broadcast transmitting system shown in FIG. 1 and then recovers the received data into original data by demodulation and equalization.

[139] Referring to FIG. 16, a demodulating unit according to one embodiment of the present invention includes a demodulator 401, a known sequence detector 403, a Viterbi decoder 404, a data deinterleaver 405, an RS decoder & non-systematic RS parity remover 406, a derandomizer 407, a main data packet remover 408, a packet de- formatter 409 and an enhanced data processor 410.

[140] A tuner tunes a frequency of a specific channel and then outputs it to the demodulator 401 and the known sequence detector 403.

[141] The demodulator 401 performs carrier recovery and timing recovery on the tuned channel frequency so that converts the input signal to a baseband signal and then outputs the baseband signal to the equalizer 402 and the known sequence detector 403.

[142] The equalizer 402 compensates distortion on channel included in the demodulated signal and then outputs the compensated signal to the Viterbi decoder 404.

[143] In this case, the known sequence detector 403 detects a known data symbol sequence inserted by a transmitting side from input/output data of the demodulator 401, i.e., data before or after the demodulation and then outputs a generated symbol sequence of the known data to the demodulator 401 and the equalizer 402.

[144] The demodulator 401 is able to enhance demodulation performance using the known data symbol sequence in timing or carrier recovery. Likewise, the equalizer 402 is able to enhance equalization performance using the known data.

[145] The Viterbi decoder 404 converts main data symbol and enhanced data symbol outputted from the equalizer 402 to bytes by Viterbi decoding and then outputs the converted bytes to the deinterleaver 405.

[146] The deinterleaver 405 performs a reverse process of the data interleaver of the transmitting side and then outputs a corresponding signal to the RS decoder & non- systematic RS parity remover 406. [147] The RS decoder and non-systematic RS parity remover 406 performs systematic RS decoding in case that the received packet is a main data packet. If the received packet is an enhanced data packet, the RS decoder & non-systematic RS parity remover 406 removes non- systematic RS parity byte from the packet and then outputs it to the de- randomizer 407.

[148] The derandomizer 407 performs a reverse process of a randomizer on an output of the RS decoder and non-systematic RS parity remover 406, inserts MPEG sync byte in a front of each packet and then outputs it by 188-byte packet unit.

[149] An output of the derandomizer 407 is outputted to both a main MPEG decoder (not shown in the drawing) and the main data packet remover 408.

[150] The main MPEG decoder performs decoding on a packet corresponding to main

MPEG only. This is because the enhanced data packet, which has null-packet PID or PID with the main data stream, is ignored by the main MPEG decoder instead of being used for the decoding.

[151] Meanwhile, the main data packet remover 408 removes 188-byte main data packet from the output of the derandomizer 407 and then outputs it to the packet deformatter 409.

[152] The packet deformatter 409 removes 4-byte MPEG header having been inserted in the enhanced data packet by the packet formatter of the transmitting side from the enhanced data packet. Also the packet deformatter 409 removes place holders for the known data from the 184-byte enhanced data packet and then outputs it to the enhanced data processor 410.

[153] And, the enhanced data processor 410 finally outputs enhanced data by performing a reverse process of the pre-processor 101 of the transmitting side on an output of the packet deformatter 409.

[154] FIG. 17 illustrates a block diagram showing the structure of a digital broadcast transmitting system according to an embodiment of the present invention. The digital broadcast transmitting system includes a pre-processor 510, a packet multiplexer 521, a data randomizer 522, a Reed-Solomon (RS) encoder/non-systematic RS encoder 523, a data interleaver 524, a parity byte replacer 525, a non-systematic RS encoder 526, a frame multiplexer 528, and a transmitting unit 530. The pre-processor 510 includes an enhanced data randomizer 511 , a RS frame encoder 512, a block processor 513 , a group formatter 514, a data deinterleaver 515, and a packet formatter 516.

[155] In the present invention having the above-described structure, main data are inputted to the packet multiplexer 521. Enhanced data are inputted to the enhanced data randomizer 511 of the pre-processor 510, wherein an additional coding process is performed so that the present invention can respond swiftly and appropriately against noise and change in channel. The enhanced data randomizer 511 randomizes the received enhanced data and outputs the randomized enhanced data to the RS frame encoder 512. At this point, by having the enhanced data randomizer 511 perform the randomizing process on the enhanced data, the randomizing process on the enhanced data by the data randomizer 522 in a later process may be omitted. Either the randomizer of the conventional broadcast system may be used as the randomizer for randomizing the enhanced data, or any other type of randomizer may be used herein.

[156] The RS frame encoder 512 receives the randomized enhanced data and performs at least one of an error correction coding process and an error detection coding process on the received data. Accordingly, by providing robustness to the enhanced data, the data can scatter group error that may occur due to a change in the frequency environment. Thus, the data can respond appropriately to the frequency environment which is very poor and liable to change. The RS frame multiplexer 512 also includes a process of mixing in row units many sets of enhanced data each having a pre-determined size. By performing an error correction coding process on the inputted enhanced data, the RS frame encoder 512 adds data required for the error correction and, then, performs an error detection coding process, thereby adding data required for the error detection process. The error correction coding uses the RS coding method, and the error detection coding uses the cyclic redundancy check (CRC) coding method. When performing the RS coding process, parity data required for the error correction are generated. And, when performing the CRC coding process, CRC data required for the error detection are generated.

[157] The RS frame encoder 512 performs CRC coding on the RS coded enhanced data in order to create the CRC code. The CRC code that is generated by the CRC coding process may be used to indicate whether the enhanced data have been damaged by an error while being transmitted through the channel. The present invention may adopt other types of error detection coding methods, apart from the CRC coding method, and may also use the error correction coding method so as to enhance the overall error correction ability of the receiving system. For example, assuming that the size of one RS frame is 187*N bytes, that (235,187)-RS coding process is performed on each column within the RS frame, and that a CRC coding process using a 2-byte (i.e., 16-bit) CRC checksum, then a RS frame having the size of 187*N bytes is expanded to a RS frame of 235*(N+2) bytes. The RS frame expanded by the RS frame encoder 512 is inputted to the block processor 513. The block processor 513 codes the RS-coded and CRC-coded enhanced data at a coding rate of G/H. Then, the block processor 513 outputs the G/H-rate coded enhanced data to the group formatter 514. In order to do so, the block processor 513 identifies the block data bytes being inputted from the RS frame encoder 512 as bits.

[158] The block processor 513 may receive supplemental information data such as signaling information, which include information on the system, and identifies the supplemental information data bytes as data bits. Herein, the supplemental information data, such as the signaling information, may equally pass through the enhanced data randomizer 511 and the RS frame encoder 512 so as to be inputted to the block processor 513. Alternatively, the supplemental information data may be directly inputted to the block processor 513 without passing through the enhanced data randomizer 511 and the RS frame encoder 512. The signaling information corresponds to information required for receiving and processing data included in the data group in the receiving system. Such signaling information includes data group information, multiplexing information, and burst information.

[159] As a G/H-rate encoder, the block processor 513 codes the inputted data at a coding rate of G/H and then outputs the G/H-rate coded data. For example, if 1 bit of the input data is coded to 2 bits and outputted, then G is equal to 1 and H is equal to 2 (i.e., G=I and H=2). Alternatively, if 1 bit of the input data is coded to 4 bits and outputted, then G is equal to 1 and H is equal to 4 (i.e., G=I and H=4). As an example of the present invention, it is assumed that the block processor 513 performs a coding process at a coding rate of 1/2 (also referred to as a 1/2-rate coding process) or a coding process at a coding rate of 1/4 (also referred to as a 1/4-rate coding process). More specifically, the block processor 513 codes the received enhanced data and supplemental information data, such as the signaling information, at either a coding rate of 1/2 or a coding rate of 1/4. Thereafter, the supplemental information data, such as the signaling information, are identified and processed as enhanced data.

[160] Since the 1/4-rate coding process has a higher coding rate than the 1/2-rate coding process, greater error correction ability may be provided. Therefore, in a later process, by allocating the 1/4-rate coded data in an area with deficient receiving performance within the group formatter 514, and by allocating the 1/2-rate coded data in an area with excellent receiving performance, the difference in the overall performance may be reduced. More specifically, in case of performing the 1/2-rate coding process, the block processor 513 receives 1 bit and codes the received 1 bit to 2 bits (Le., 1 symbol). Then, the block processor 513 outputs the processed 2 bits (or 1 symbol). On the other hand, in case of performing the 1/4-rate coding process, the block processor 513 receives 1 bit and codes the received 1 bit to 4 bits (i.e., 2 symbols). Then, the block processor 513 outputs the processed 4 bits (or 2 symbols). Additionally, the block processor 513 performs a block interleaving process in symbol units on the symbol-coded data. Subsequently, the block processor 513 converts to bytes the data symbols that are block-interleaved and have the order rearranged.

[161] The group formatter 514 inserts the enhanced data outputted from the block processor 513 (herein, the enhanced data may include supplemental information data such as signaling information including transmission information) in a corresponding area within the data group, which is configured according to a pre-defined rule. Furthermore, in relation with the data deinterleaving process, various types of places holders or known data are also inserted in corresponding areas within the data group. At this point, the data group may be described by at least one hierarchical area. Herein, the data allocated to the each area may vary depending upon the characteristic of each hierarchical area. Additionally, each group is configured to include a field synchronization signal.

[162] The present invention shows an example of the data group being divided into three hierarchical areas: a head area, a body area, and a tail area. Accordingly, in the data group that is inputted for the data deinterleaving process, data are first inputted to the head area, then inputted to the body area, and inputted finally to the tail area. In the example of the present invention, the head, body, and tail areas are configured so that the body area is not mixed with the main data area within the data group. Furthermore, in the present invention, the head, body, and tail areas may each be divided into lower hierarchical areas. For example, the head area may be divided into 3 lower hierarchical areas: a far head (FH) area, a middle head (MH) area, and a near head (NH) area. The body area may be divided into 4 lower hierarchical areas: a first lower body (B l) area, a second lower body (B2) area, a third lower body (B3) area, and a fourth lower body (B4) area. And, finally, the tail area may be divided into 2 lower hierarchical areas: a far tail (FT) area and a near tail (NT) area.

[163] In the example of the present invention, the group formatter 514 inserts the enhanced data being outputted from the block processor 513 to the middle head (MH) area, the near head (NH) area, the first to fourth lower body (B 1 to B4) areas, and the near tail (NT) area. Herein, the type of enhanced data may vary depending upon the characteristic of each area. The data group is divided into a plurality of areas so that each area may be used for different purposes. More specifically, areas having less interference with the main data may show more enhanced receiving performance as compared with area having more interference with the main data. Additionally, when using the system in which the known data are inserted in the data group and then transmitted, and when a long set of consecutive known data is to be periodically (or regularly) inserted in the enhanced data, the body area is capable of regularly receiving such enhanced data having a predetermined length. However, since the enhanced data may be mixed with the main data in the head and tail areas, it is difficult to regularly insert the known data in these areas, and it is also difficult to insert long known data sets that are consecutive in these areas.

[164] Details such as the size of the data group, the number of hierarchical areas within the data group and the size of each hierarchical area, and the number of enhanced data bytes that may be inserted in each hierarchical area may vary depending upon the design of the system designer. Therefore, the above-described embodiment is merely an example that can facilitate the description of the present invention. In the group formatter 514, the data group may be configured to include a position (or place) in which the field synchronization signal is to be inserted. When assuming that the data group is divided into a plurality of hierarchical areas as described above, the block processor 513 may code the data that are to be inserted in each area at different coding rates.

[165] In the present invention, based upon the areas that are each expected to show different performance after the equalization process when using the channel information that may be used for the channel equalization process in the receiving system, a different coding rate may be applied to each of these areas. For example, the block processor 513 codes the enhanced data that are to be inserted in the near head (NH) area and the first to fourth lower body (Bl to B4) areas at a 1/2-coding rate. Thereafter, the group formatter 514 may insert the 1/2-rate coded enhanced data in the near head (NH) area and the first to fourth lower body (Bl to B4) areas. On the other hand, the block processor 513 codes the enhanced data that are to be inserted in the middle head (MH) area and the near tail (NT) area at a 1/4-coding rate, which has greater error correction ability than the 1/2-coding rate. Subsequently, the group formatter 514 may insert the 1/2-rate coded enhanced data in the middle head (MH) area and the near tail (NT) area. Furthermore, the block processor 513 codes the enhanced data that are to be inserted in the far head (FH) area and the far tail (FT) area at a coding rate having even greater error correction ability than the 1/4-coding rate. Thereafter, the group formatter 514 may inserts the coded enhanced data either in the far head (FH) and far tail (FT) areas or in a reserved area for future usage.

[166] Apart from the enhanced data, the group formatter 513 may also insert supplemental information data such as signaling information indicating the overall transmission information in the data group. Also, apart from the coded enhanced data outputted from the block processor 513, and in relation with the data deinterleaving process in a later process, the group formatter 514 may also insert a MPEG header place holder, a non-systematic RS parity place holder, and a main data place holder in the data group. Herein, the main data group place holder is inserted because the enhanced data and the main data may be mixed in the head and tail areas depending upon the input of the data deinterleaver. For example, based upon the output of the data after being deinterleaved, the place holder for the MPEG header may be allocated to the front of each data packet. Additionally, the group formatter 514 may either insert known data generated according to a pre-defined rule, or insert a known data place holder for inserting known data in a later process. Furthermore, a place holder for the initialization of the trellis encoder module 527 is inserted in a corresponding area. For example, the initialization data place holder may be inserted at the beginning (or front) of the data place sequence.

[167] The output of the group formatter 514 is inputted to the data deinterleaver 515.

And, the data deinterleaver 515 performs an inverse process of the data interleaver deinterleaving the data and place holder within the data group being outputted from the group formatter 514. Thereafter, the data deinterleaver 515 outputs the deinterelaved data to the packet formatter 516. Among the data deinterleaved and inputted, the packet formatter 516 removes the main data place holder and RS parity place holder that were allocated for the deinterleaving process from the inputted deinterleaved data. Thereafter, the remaining portion of the corresponding data is grouped, and 4 bytes of MPEG header are inserted therein. The 4-byte MPEG header is configured of a 1-byte MPEG synchronization byte added to the 3 -byte MPEG header place holder.

[168] When the group formatter 514 inserts the known data place holder, the packet formatter 516 may either insert actual known data in the known data place holder or output the known data place holder without any change or modification for a replacement insertion in a later process. Afterwards, the packet formatter 516 divides the data within the above-described packet-formatted data group into 188-byte unit enhanced data packets (i.e., MPEG TS packets), which are then provided to the packet multiplexer 521. The packet multiplexer 521 multiplexes the 188-byte unit enhanced data packet and main data packet outputted from the packet formatter 516 according to a pre-defined multiplexing method. Subsequently, the multiplexed data packets are outputted to the data randomizer 522. The multiplexing method may be modified or altered in accordance with diverse variables of the system design.

[169] As an example of the multiplexing method of the packet multiplexer 521, the enhanced data burst section and the main data section may be identified along a time axis (or a chronological axis) and may be alternately repeated. At this point, the enhanced data burst section may transmit at least one data group, and the main data section may transmit only the main data. The enhanced data burst section may also transmit the main data. If the enhanced data are outputted in a burst structure, as described above, the receiving system receiving only the enhanced data may turn the power on only during the burst section so as to receive the enhanced data, and may turn the power off during the main data section in which main data are transmitted, so as to prevent the main data from being received, thereby reducing the power consumption of the receiving system.

[170] When the data being inputted correspond to the main data packet, the data randomizer 522 performs the same randomizing process of the conventional randomizer. More specifically, the MPEG synchronization byte included in the main data packet is discarded and a pseudo random byte generated from the remaining 187 bytes is used so as to randomize the data. Thereafter, the randomized data are outputted to the RS encoder/non-systematic RS encoder 523. However, when the inputted data correspond to the enhanced data packet, the MPEG synchronization byte of the 4-byte MPEG header included in the enhanced data packet is discarded, and data randomizing is performed only on the remaining 3 -byte MPEG header. Randomizing is not performed on the remaining portion of the enhanced data. Instead, the remaining portion of the enhanced data is outputted to the RS encoder/non-systematic RS encoder 523. This is because the randomizing process has already been performed on the enhanced data by the enhanced data randomizer 511 in an earlier process. Herein, a data randomizing process may or may not be performed on the known data (or known data place holder) and the initialization data place holder included in the enhanced data packet.

[171] The RS encoder/non-systematic RS encoder 523 RS-codes the data randomized by the data randomizer 522 or the data bypassing the data randomizer 522. Then, the RS encoder/non- systematic RS encoder 523 adds a 20-byte RS parity to the coded data, thereby outputting the RS-parity-added data to the data interleaver 524. At this point, if the inputted data correspond to the main data packet, the RS encoder/non-systematic RS encoder 523 performs a systematic RS-coding process identical to that of the conventional receiving system on the inputted data, thereby adding the 20-byte RS parity at the end of the 187-byte data. Alternatively, if the inputted data correspond to the enhanced data packet, the 20 bytes of RS parity gained by performing the non- systematic RS-coding are respectively inserted in the decided parity byte places within the enhanced data packet. Herein, the data interleaver 524 corresponds to a byte unit convolutional interleaver. The output of the data interleaver 524 is inputted to the parity byte replacer 525 and the non-systematic RS encoder 526.

[172] Meanwhile, a memory within the trellis encoding module 527, which is positioned after the parity byte replacer 525, should first be initialized in order to allow the output data of the trellis encoding module 527 so as to become the known data defined based upon an agreement between the receiving system and the transmitting system. More specifically, the memory of the trellis encoding module 527 should first be initialized before the known data sequence being inputted is trellis -encoded. At this point, the beginning of the known data sequence that is inputted corresponds to the initialization data place holder inserted by the group formatter 514 and not the actual known data. Therefore, a process of generating initialization data right before the trellis -encoding of the known data sequence being inputted and a process of replacing the initialization data place holder of the corresponding trellis encoding module memory with the newly generated initialization data are required. [173] A value of the trellis memory initialization data is decided based upon the memory status of the trellis encoding module 527, thereby generating the trellis memory initialization data accordingly. Due to the influence of the replace initialization data, a process of recalculating the RS parity, thereby replacing the RS parity outputted from the trellis encoding module 527 with the newly calculated RS parity is required. Accordingly, the non-systematic RS encoder 526 receives the enhanced data packet including the initialization data place holder that is to be replaced with the initialization data from the data interleaver 524 and also receives the initialization data from the trellis encoding module 527. Thereafter, among the received enhanced data packet, the initialization data place holder is replaced with the initialization data. Subsequently, the RS parity data added to the enhanced data packet are removed. Then, a new non- systematic RS parity is calculated and outputted to the parity byte replacer 525. Accordingly, the parity byte replacer 525 selects the output of the data interleaver 524 as the data within the enhanced data packet, and selects the output of the non-systematic RS encoder 526 as the RS parity. Thereafter, the parity byte replacer 525 outputs the selected data.

[174] Meanwhile, if the main data packet is inputted, or if the enhanced data packet that does not include the initialization data place holder that is to be replaced, the parity byte replacer 525 selects the data and RS parity outputted from the data interleaver 524 and directly outputs the selected data to the trellis encoding module 527 without modification. The trellis encoding module 527 converts the byte-unit data to symbol-unit data and 12-way interleaves and trellis-encodes the converted data, which are then outputted to the frame multiplexer 528. The frame multiplexer 528 inserts field synchronization and segment synchronization signals in the output of the trellis encoding module 527 and then outputs the processed data to the transmitting unit 530. Herein, the transmitting unit 530 includes a pilot inserter 531, a modulator 532, and a radio frequency (RF) up-converter 533. The operation of the transmitting unit 530 is identical to the conventional transmitters. Therefore, a detailed description of the same will be omitted for simplicity.

[175] FIG. 18 illustrates a block diagram of a demodulating unit included in the receiving system according to another embodiment of the present invention. Herein, the demodulating unit may effectively process signals transmitted from the transmitting system shown in FIG. 17. Referring to FIG. 18, the demodulating unit includes a demodulator 601, a channel equalizer 602, a known sequence detector 603, a block decoder 604, an enhanced data deformatter 605, a RS frame decoder 606, an enhanced data derandomizer 607, a data deinterleaver 608, a RS decoder 609, and a main data derandomizer 910. For simplicity, the demodulator 601, the channel equalizer 602, the known sequence detector 603, the block decoder 604, the enhanced data deformatter 605, the RS frame decoder 606, and the enhanced data derandomizer 607 will be referred to as an enhanced data processor. And, the data deinterleaver 608, the RS decoder 609, and the main data derandomizer 910 will be referred to as a main data processor.

[176] More specifically, the enhanced data including known data and the main data are received through the tuner and inputted to the demodulator 601 and the known sequence detector 603. The demodulator 601 performs automatic gain control, carrier wave recovery, and timing recovery on the data that are being inputted, thereby creating baseband data, which are then outputted to the equalizer 602 and the known sequence detector 603. The equalizer 602 compensates the distortion within the channel included in the demodulated data. Then, the equalizer 602 outputs the compensated data to the block decoder 604.

[177] At this point, the known sequence detector 603 detects the known data place inserted by the transmitting system to the input/output data of the demodulator 601 (i.e. , data prior to demodulation or data after demodulation). Then, along with the position information, the known sequence detector 603 outputs the symbol sequence of the known data generated from the corresponding position to the demodulator 601 and the equalizer 602. Additionally, the known sequence detector 603 outputs information enabling the block decoder 604 to identify the enhanced data being additionally encoded by the transmitting system and the main data that are not additionally encoded to the block decoder 604. Furthermore, although the connection is not shown in FIG. 18, the information detected by the known sequence detector 603 may be used in the overall receiving system and may also be used in the enhanced data formatter 605 and the RS frame decoder 606.

[178] By using the known data symbol sequence when performing the timing recovery or carrier wave recovery, the demodulating performance of the demodulator 601 may be enhanced. Similarly, by using the known data, the channel equalizing performance of the channel equalizer 602 may be enhanced. Furthermore, by feeding-back the demodulation result of the block demodulator 604, the channel equalizing performance may also be enhanced. Herein, the channel equalizer 602 may perform channel equalization through various methods. In the present invention, a method of estimating a channel impulse response (CIR) for performing the channel equalization process will be given as an example of the present invention. More specifically, in the present invention, the channel impulse response (CIR) is differently estimated and applied in accordance with each hierarchical area within the data group that are transmitted from the transmitting system. Furthermore, by using the known data having the position (or place) and contents pre-known according to an agreement between the transmitting system and the receiving system, so as to estimate the CIR, the channel equalization process may be processed with more stability.

[179] In the present invention, one data group that is inputted for channel equalization is divided into three hierarchical areas: a head area, a body area, and a tail area. Then, each of the areas is divided into lower hierarchical areas. More specifically, the head area may be divided into a far head (FH) area, a middle head (MH) area, and a near head (NH) area. And, the tail area may be divided into a far tail (FT) area and a near tail (NT) area. Furthermore, based upon a long known data sequence, the body area may be divided into 4 lower hierarchical areas: a first lower body (Bl) area, a second lower body (B2) area, a third lower body (B3) area, and a fourth lower body (B4) area. In performing channel equalization on the data within the data group by using the CIR estimated from the field synchronization signal and the known data sequence, and in accordance with the characteristic of each area, either one of the estimated CIRs may be directly used without modification, or a CIR created by interpolating or extrapolating a plurality of CIRs may be used.

[180] Meanwhile, if the data being channel equalized and then inputted to the block decoder 604 correspond to the enhanced data on which additional encoding and trellis encoding are both performed by the transmitting system, trellis-decoding and additional decoding processes are performed as inverse processes of the transmitting system. Alternatively, if the data being channel equalized and then inputted to the block decoder 604 correspond to the main data on which additional encoding is not performed and only trellis-encoding is performed by the transmitting system, only the trellis-decoding process is performed. The data group decoded by the block decoder 604 is inputted to the enhanced data deformatter 605, and the main data packet is inputted to the data deinterleaver 608.

[181] More specifically, if the inputted data correspond to the main data, the block decoder 604 performs Viterbi decoding on the inputted data, so as to either output a hard decision value or hard-decide a soft decision value and output the hard-decided result. On the other hand, if the inputted correspond to the enhanced data, the block decoder 604 outputs either a hard decision value or a soft decision value on the inputted enhanced data. In other words, if the data inputted to the block decoder 604 correspond to the enhanced data, the block decoder 604 performs a decoding process on the data encoded by the block processor and the trellis encoder of the transmitting system. At this point, the output of the RS frame encoder included in the pre-processor of the transmitting system becomes an external code, and the output of the block processor and the trellis encoder becomes an internal code. In order to show maximum performance of the external code when decoding such connection codes, the decoder of the internal code should output a soft decision value. Therefore, the block decoder 604 may output a hard decision value on the enhanced data. However, when required, it is more preferable that the block decoder 604 outputs a soft decision value.

[182] The present invention may also be used for configuring a reliability map using the soft decision value. The reliability map determines and indicates whether a byte corresponding to a group of 8 bits decided by the code of the soft decision value is reliable. For example, when an absolute value of the soft decision value exceeds a predetermined threshold value, the value of the bit corresponding to the soft decision value code is determined to be reliable. However, if the absolute value does not exceed the pre-determined threshold value, then the value of the corresponding bit is determined to be not reliable. Further, if at least one bit among the group of 8 bits, which are determined based upon the soft decision value, is determined to be not reliable, then the reliability map indicates that the entire byte is not reliable. Herein, the process of determining the reliability by 1-bit units is merely exemplary. The corresponding byte may also be indicated to be not reliable if a plurality of bits (e.g., 4 bits) is determined to be not reliable.

[183] Conversely, when all of the bits are determined to be reliable within one byte (i.e., when the absolute value of the soft value of all bits exceeds the pre-determined threshold value), then the reliability map determines and indicates that the corresponding data byte is reliable. Similarly, when more than 4 bits are determined to be reliable within one data byte, then the reliability map determines and indicates that the corresponding data byte is reliable. The estimated numbers are merely exemplary and do not limit the scope and spirit of the present invention. Herein, the reliability map may be used when performing error correction decoding processes.

[184] Meanwhile, the data deinterleaver 608, the RS decoder 609, and the main data de- randomizer 910 are blocks required for receiving the main data. These blocks may not be required in a receiving system structure that receives only the enhanced data. The data deinterleaver 608 performs an inverse process of the data interleaver of the transmitting system. More specifically, the data deinterleaver 608 deinterleaves the main data being outputted from the block decode 604 and outputs the deinterleaved data to the RS decoder 609. The RS decoder 609 performs systematic RS decoding on the deinterleaved data and outputs the systematically decoded data to the main data de- randomizer 910. The main data derandomizer 910 receives the data outputted from the RS decoder 609 so as to generate the same pseudo random byte as that of the randomizer in the transmitting system. The main data derandomizer 910 then performs a bitwise exclusive OR (XOR) operation on the generated pseudo random data byte, thereby inserting the MPEG synchronization bytes to the beginning of each packet so as to output the data in 188-byte main data packet units.

[185] Herein, the format of the data being outputted to the enhanced data deformatter 605 from the block decoder 604 is a data group format. At this point, the enhanced data de- formatter 605 already knows the structure of the input data. Therefore, the enhanced data deformatter 605 identifies the system information including signaling information and the enhanced data from the data group. Thereafter, the identified signaling information is transmitted to where the system information is required, and the enhanced data are outputted to the RS frame decoder 606. The enhanced data deformatter 605 removes the known data, trellis initialization data, and MPEG header that were included in the main data and the data group and also removes the RS parity that was added by the RS encoder/non-systematic RS encoder of the transmitting system. Thereafter, the processed data are outputted to the RS frame decoder 606.

[186] More specifically, the RS frame decoder 606 receives the RS-coded and CRC- coded enhanced data from the enhanced data deformatter 605 so as to configure the RS frame. The RS frame decoder 606 performs an inverse process of the RS frame encoder included in the transmitting system, thereby correcting the errors within the RS frame. Then, the 1-byte MPEG synchronization byte, which was removed during the RS frame coding process, is added to the error corrected enhanced data packet. Subsequently, the processed data are outputted to the enhanced data derandomizer 607. Herein, the enhanced data derandomizer 607 performs a derandomizing process, which corresponds to an inverse process of the enhanced data randomizer included in the transmitting system, on the received enhanced data. Then, by outputting the processed data, the enhanced data transmitted from the transmitting system can be obtained.

[187] According to an embodiment of the present invention, the RS frame decoder 606 may also be configured as follows. The RS frame decoder 606 may perform a CRC syndrome check on the RS frame, thereby verifying whether or not an error has occurred in each row. Subsequently, the CRC checksum is removed and the presence of an error is indicated on a CRC error flag corresponding to each row. Then, a RS decoding process is performed on the RS frame having the CRC checksum removed in a column direction. At this point, depending upon the number of CRC error flags, a RS erasure decoding process may be performed. More specifically, by checking the CRC error flags corresponding to each row within the RS frame, the number of CRC error flags may be determined whether it is greater or smaller than the maximum number of errors, when RS decoding the number of rows with errors (or erroneous rows) in the column direction. Herein, the maximum number of errors corresponds to the number of parity bytes inserted during the RS decoding process. As an example of the present invention, it is assumed that 48 parity bytes are added to each column.

[188] If the number of rows with CRC errors is equal to or smaller than the maximum number of errors (e.g., 48), which may be corrected by the RS erasure decoding process, the RS erasure decoding process is performed on the RS frame in the column direction. Thereafter, the 48 bytes of parity data that were added at the end of each column are removed. However, if the number of rows with CRC errors is greater than the maximum number of errors (e.g., 48), which may be corrected by the RS erasure decoding process, the RS erasure decoding process cannot be performed. In this case, the error may be corrected by performing a general RS decoding process.

[189] As another embodiment of the present invention, the error correction ability may be enhanced by using the reliability map created when configuring the RS frame from the soft decision value. More specifically, the RS frame decoder 606 compares the absolute value of the soft decision value obtained from the block decoder 604 to the pre-determined threshold value so as to determine the reliability of the bit values that are decided by the code of the corresponding soft decision value. Then, 8 bits are grouped to configure a byte. Then, the reliability information of the corresponding byte is indicated on the reliability map. Therefore, even if a specific row is determined to have CRC errors as a result of the CRC syndrome checking process of the corresponding row, it is not assumed that all of the data bytes included in the corresponding row have error. Instead, only the data bytes that are determined to be not reliable, after referring to the reliability information on the reliability map, are set to have errors. In other words, regardless of the presence of CRC errors in the corresponding row, only the data bytes that are determined to be not reliable (or unreliable) by the reliability map are set as erasure points.

[190] Thereafter, if the number of erasure points for each column is equal to or smaller than the maximum number of errors (e.g., 48), the RS erasure decoding process is performed on the corresponding the column. Conversely, if the number of erasure points is greater than the maximum number of errors (e.g., 48), which may be corrected by the RS erasure decoding process, a general decoding process is performed on the corresponding column. In other words, if the number of rows having CRC errors is greater than the maximum number of errors (e.g., 48), which may be corrected by the RS erasure decoding process, either a RS erasure decoding process or a general RS decoding process is performed on a particular column in accordance with the number of erasure point within the corresponding column, wherein the number is decided based upon the reliability information on the reliability map. When the above- described process is performed, the error correction decoding process is performed in the direction of all of the columns included in the RS frame. Thereafter, the 48 bytes of parity data added to the end of each column are removed.

[191] FIG. 19 illustrates a block diagram showing the structure of a digital broadcast receiving system according to an embodiment of the present invention. Referring to FIG. 19, the digital broadcast receiving system includes a tuner 701, a demodulating unit 702, a demultiplexer 703, an audio decoder 704, a video decoder 705, a native TV application manager 706, a channel manager 707, a channel map 708, a first memory 709, a data decoder 710, a second memory 711, a system manager 712, a data broadcasting application manager 713, a storage controller 714, and a third memory 715. Herein, the third memory 715 is a mass storage device, such as a hard disk drive (HDD) or a memory chip. The tuner 701 tunes a frequency of a specific channel through any one of an antenna, cable, and satellite. Then, the tuner 701 down-converts the tuned frequency to an intermediate frequency (IF), which is then outputted to the demodulating unit 702. At this point, the tuner 701 is controlled by the channel manager 707. Additionally, the result and strength of the broadcast signal of the tuned channel are also reported to the channel manager 707. The data that are being received by the frequency of the tuned specific channel include main data, enhanced data, and table data for decoding the main data and enhanced data.

[192] In the embodiment of the present invention, examples of the enhanced data may include data provided for data service, such as Java application data, HTML application data, XML data, and so on. The data provided for such data services may correspond either to a Java class file for the Java application, or to a directory file designating positions (or locations) of such files. Furthermore, such data may also correspond to an audio file and/or a video file used in each application. The data services may include weather forecast services, traffic information services, stock information services, services providing information quiz programs providing audience participation services, real time poll, user interactive education programs, gaming services, services providing information on soap opera (or TV series) synopsis, characters, original sound track, filing sites, services providing information on past sports matches, profiles and accomplishments of sports players, product information and product ordering services, services providing information on broadcast programs by media type, airing time, subject, and so on. The types of data services described above are only exemplary and are not limited only to the examples given herein. Furthermore, depending upon the embodiment of the present invention, the enhanced data may correspond to meta data. For example, the meta data use the XML application so as to be transmitted through a DSM-CC protocol.

[193] The demodulating unit 702 performs VSB -demodulation and channel equalization on the signal being outputted from the tuner 701, thereby identifying the main data and the enhanced data. Thereafter, the identified main data and enhanced data are outputted in TS packet units. Examples of the demodulating unit 702 is shown in FIG. 16 and FIG. 18. The demodulating unit shown in FIG. 16 and FIG. 18 is merely exemplary and the scope of the present invention is not limited to the examples set forth herein. In the embodiment given as an example of the present invention, only the enhanced data packet outputted from the demodulating unit 702 is inputted to the demultiplexer 703. In this case, the main data packet is inputted to another demultiplexer (not shown) that processes main data packets. Herein, the storage controller 714 is also connected to the other demultiplexer in order to store the main data after processing the main data packets. The demultiplexer of the present invention may also be designed to process both enhanced data packets and main data packets in a single demultiplexer.

[194] The storage controller 714 is interfaced with the demultipelxer so as to control instant recording, reserved (or pre-programmed) recording, time shift, and so on of the enhanced data and/or main data. For example, when one of instant recording, reserved (or pre-programmed) recording, and time shift is set and programmed in the receiving system (or receiver) shown in FIG. 19, the corresponding enhanced data and/or main data that are inputted to the demultiplexer are stored in the third memory 715 in accordance with the control of the storage controller 714. The third memory 715 may be described as a temporary storage area and/or a permanent storage area. Herein, the temporary storage area is used for the time shifting function, and the permanent storage area is used for a permanent storage of data according to the user's choice (or decision).

[195] When the data stored in the third memory 715 need to be reproduced (or played), the storage controller 714 reads the corresponding data stored in the third memory 715 and outputs the read data to the corresponding demultiplexer (e.g., the enhanced data are outputted to the demultiplexer 703 shown in FIG. 19). At this point, according to the embodiment of the present invention, since the storage capacity of the third memory 715 is limited, the compression encoded enhanced data and/or main data that are being inputted are directly stored in the third memory 715 without any modification for the efficiency of the storage capacity. In this case, depending upon the reproduction (or reading) command, the data read from the third memory 715 pass trough the demultiplexer so as to be inputted to the corresponding decoder, thereby being restored to the initial state.

[196] The storage controller 714 may control the reproduction (or play), fast-forward, rewind, slow motion, instant replay functions of the data that are already stored in the third memory 715 or presently being buffered. Herein, the instant replay function corresponds to repeatedly viewing scenes that the viewer (or user) wishes to view once again. The instant replay function may be performed on stored data and also on data that are currently being received in real time by associating the instant replay function with the time shift function. If the data being inputted correspond to the analog format, for example, if the transmission mode is NTSC, PAL, and so on, the storage controller 714 compression encodes the inputted data and stored the compression-encoded data to the third memory 715. In order to do so, the storage controller 714 may include an encoder, wherein the encoder may be embodied as one of software, middleware, and hardware. Herein, an MPEG encoder may be used as the encoder according to an embodiment of the present invention. The encoder may also be provided outside of the storage controller 714.

[197] Meanwhile, in order to prevent illegal duplication (or copies) of the input data being stored in the third memory 715, the storage controller 714 scrambles the input data and stores the scrambled data in the third memory 715. Accordingly, the storage controller 714 may include a scramble algorithm for scrambling the data stored in the third memory 715 and a descramble algorithm for descrambling the data read from the third memory 715. Herein, the definition of scramble includes encryption, and the definition of descramble includes decryption. The scramble method may include using an arbitrary key (e.g., control word) to modify a desired set of data, and also a method of mixing signals.

[198] Meanwhile, the demultiplexer 703 receives the real-time data outputted from the demodulating unit 702 or the data read from the third memory 715 and demultiplexes the received data. In the example given in the present invention, the demultiplexer 703 performs demultiplexing on the enhanced data packet. Therefore, in the present invention, the receiving and processing of the enhanced data will be described in detail. It should also be noted that a detailed description of the processing of the main data will be omitted for simplicity starting from the description of the demultiplexer 703 and the subsequent elements.

[199] The demultiplexer 703 demultiplexes enhanced data and program specific information/program and system information protocol (PSI/PSIP) tables from the enhanced data packet inputted in accordance with the control of the data decoder 710. Thereafter, the demultiplexed enhanced data and PSI/PSIP tables are outputted to the data decoder 710 in a section format. In order to extract the enhanced data from the channel through which enhanced data are transmitted and to decode the extracted enhanced data, system information is required. Such system information may also be referred to as service information. The system information may include channel information, event information, etc. In the embodiment of the present invention, the PSI/ PSIP tables are applied as the system information. However, the present invention is not limited to the example set forth herein. More specifically, regardless of the name, any protocol transmitting system information in a table format may be applied in the present invention.

[200] The PSI table is an MPEG-2 system standard defined for identifying the channels and the programs. The PSIP table is an advanced television systems committee (ATSC) standard that can identify the channels and the programs. The PSI table may include a program association table (PAT), a conditional access table (CAT), a program map table (PMT), and a network information table (NIT). Herein, the PAT corresponds to special information that is transmitted by a data packet having a PID of ¹O'. The PAT transmits PID information of the PMT and PID information of the NIT corresponding to each program. The CAT transmits information on a paid broadcast system used by the transmitting system. The PMT transmits PID information of a transport stream (TS) packet, in which program identification numbers and individual bit sequences of video and audio data configuring the corresponding program are transmitted, and the PID information, in which PCR is transmitted. The NIT transmits information of the actual transmission network.

[201] The PSIP table may include a virtual channel table (VCT), a system time table

(STT), a rating region table (RRT), an extended text table (ETT), a direct channel change table (DCCT), an event information table (EIT), and a master guide table (MGT). The VCT transmits information on virtual channels, such as channel information for selecting channels and information such as packet identification (PID) numbers for receiving the audio and/or video data. More specifically, when the VCT is parsed, the PID of the audio/video data of the broadcast program may be known. Herein, the corresponding audio/video data are transmitted within the channel along with the channel name and the channel number. The STT transmits information on the current data and timing information. The RRT transmits information on region and consultation organs for program ratings. The ETT transmits additional description of a specific channel and broadcast program. The EIT transmits information on virtual channel events (e.g., program title, program start time, etc.). The DCCT/DCCSCT transmits information associated with automatic (or direct) channel change. And, the MGT transmits the versions and PID information of the above-mentioned tables included in the PSIP.

[202] Each of the above-described tables included in the PSI/PSIP is configured of a basic unit referred to as a "section" and a combination of one or more sections forms a table. For example, the VCT may be divided into 256 sections. Herein, one section may include a plurality of virtual channel information. However, a single set of virtual channel information is not divided into two or more sections. At this point, the receiving system may parse and decode the data for the data service that are transmitting by using only the tables included in the PSI, or only the tables included in the PISP, or a combination of tables included in both the PSI and the PSIP. In order to parse and decode the data for the data service, at least one of the PAT and PMT included in the PSI, and the VCT included in the PSIP is required. For example, the PAT may include the system information for transmitting the data corresponding to the data service, and the PID of the PMT corresponding to the data service data (or program number). The PMT may include the PID of the TS packet used for transmitting the data service data. The VCT may include information on the virtual channel for transmitting the data service data, and the PID of the TS packet for transmitting the data service data. [203] Meanwhile, depending upon the embodiment of the present invention, a DVB-SI may be applied instead of the PSIP. The DVB-SI may include a network information table (NIT), a service description table (SDT), an event information table (EIT), and a time and data table (TDT). The DVB-SI may be used in combination with the above- described PSI. Herein, the NIT divides the services corresponding to particular network providers by specific groups. The NIT includes all tuning information that are used during the IRD set-up. The NIT may be used for informing or notifying any change in the tuning information. The SDT includes the service name and different parameters associated with each service corresponding to a particular MPEG multiplex. The EIT is used for transmitting information associated with all events occurring in the MPEG multiplex. The EIT includes information on the current transmission and also includes information selectively containing different transmission streams that may be received by the IRD. And, the TDT is used for updating the clock included in the IRD.

[204] Furthermore, three selective SI tables (i.e., a bouquet associate table (BAT), a running status table (RST), and a stuffing table (ST)) may also be included. More specifically, the bouquet associate table (BAT) provides a service grouping method enabling the IRD to provide services to the viewers. Each specific service may belong to at least one 'bouquet' unit. A running status table (RST) section is used for promptly and instantly updating at least one event execution status. The execution status section is transmitted only once at the changing point of the event status. Other SI tables are generally transmitted several times. The stuffing table (ST) may be used for replacing or discarding a subsidiary table or the entire SI tables.

[205] In the present invention, the enhanced data included in the payload within the TS packet consist of a digital storage media-command and control (DSM-CC) section format. However, the TS packet including the data service data may correspond either to a packetized elementary stream (PES) type or to a section type. More specifically, either the PES type data service data configure the TS packet, or the section type data service data configure the TS packet. The TS packet configured of the section type data will be given as the example of the present invention. At this point, the data service data are includes in the digital storage media-command and control (DSM-CC) section. Herein, the DSM-CC section is then configured of a 188-byte unit TS packet.

[206] Furthermore, the packet identification of the TS packet configuring the DSM-CC section is included in a data service table (DST). When transmitting the DST, '0x95' is assigned as the value of a stream_type field included in the service location descriptor of the PMT or the VCT. More specifically, when the PMT or VCT streamjype field value is '0x95', the receiving system may acknowledge that data broadcasting including enhanced data (i.e., the enhanced data) is being received. At this point, the enhanced data may be transmitted by a data carousel method. The data carousel method corresponds to repeatedly transmitting identical data on a regular basis.

[207] At this point, according to the control of the data decoder 710, the demultiplexer

703 performs section filtering, thereby discarding repetitive sections and outputting only the non-repetitive sections to the data decoder 710. The demultiplexer 703 may also output only the sections configuring desired tables (e.g., VCT) to the data decoder 710 by section filtering. Herein, the VCT may include a specific descriptor for the enhanced data. However, the present invention does not exclude the possibilities of the enhanced data being included in other tables, such as the PMT. The section filtering method may include a method of verifying the PID of a table defined by the MGT, such as the VCT, prior to performing the section filtering process. Alternatively, the section filtering method may also include a method of directly performing the section filtering process without verifying the MGT, when the VCT includes a fixed PID (i.e., a base PID). At this point, the demultiplexer 703 performs the section filtering process by referring to a table_id field, a version_number field, a section_number field, etc.

[208] As described above, the method of defining the PID of the VCT broadly includes two different methods. Herein, the PID of the VCT is a packet identifier required for identifying the VCT from other tables. The first method consists of setting the PID of the VCT so that it is dependent to the MGT. In this case, the receiving system cannot directly verify the VCT among the many PSI and/or PSIP tables. Instead, the receiving system must check the PID defined in the MGT in order to read the VCT. Herein, the MGT defines the PID, size, version number, and so on, of diverse tables. The second method consists of setting the PID of the VCT so that the PID is given a base PID value (or a fixed PID value), thereby being independent from the MGT. In this case, unlike in the first method, the VCT according to the present invention may be identified without having to verify every single PID included in the MGT. Evidently, an agreement on the base PID must be previously made between the transmitting system and the receiving system.

[209] Meanwhile, in the embodiment of the present invention, the demultiplexer 703 may output only an application information table (AIT) to the data decoder 710 by section filtering. The AIT includes information on an application being operated in the receiving system for the data service. The AIT may also be referred to as an XAIT, and an AMT. Therefore, any table including application information may correspond to the following description. When the AIT is transmitted, a value of '0x05' may be assigned to a stream_type field of the PMT. The AIT may include application information, such as application name, application version, application priority, application ID, application status (i.e., auto-start, user-specific settings, kill, etc.), application type (i.e., Java or HTML), position (or location) of stream including application class and data files, application platform directory, and location of application icon.

[210] In the method for detecting application information for the data service by using the

AIT, component_tag, original_network_id, transport_stream_id, and service_id fields may be used for detecting the application information. The component_tag field designates an elementary stream carrying a DSI of a corresponding object carousel. The original_network_id field indicates a DVB-SI original_network_id of the TS providing transport connection. The transport_stream_id field indicates the MPEG TS of the TS providing transport connection, and the service_id field indicates the DVB- SI of the service providing transport connection. Information on a specific channel may be obtained by using the original_network_id field, the transport_stream_id field, and the service_id field. The data service data, such as the application data, detected by using the above-described method may be stored in the second memory 711 by the data decoder 710.

[211] The data decoder 710 parses the DSM-CC section configuring the demultiplexed enhanced data. Then, the enhanced data corresponding to the parsed result are stored as a database in the second memory 711. The data decoder 710 groups a plurality of sections having the same table identification (table_id) so as to configure a table, which is then parsed. Thereafter, the parsed result is stored as a database in the second memory 711. At this point, by parsing data and/or sections, the data decoder 710 reads all of the remaining actual section data that are not section-filtered by the demultiplexer 703. Then, the data decoder 710 stores the read data to the second memory 711. The second memory 711 corresponds to a table and data carousel database storing system information parsed from tables and enhanced data parsed from the DSM-CC section. Herein, a table_id field, a section_number field, and a last_section_number field included in the table may be used to indicate whether the corresponding table is configured of a single section or a plurality of sections. For example, TS packets having the PID of the VCT are grouped to form a section, and sections having table identifiers allocated to the VCT are grouped to form the VCT.

[212] When the VCT is parsed, information on the virtual channel to which enhanced data are transmitted may be obtained. The obtained application identification information, service component identification information, and service information corresponding to the data service may either be stored in the second memory 711 or be outputted to the data broadcasting application manager 713. In addition, reference may be made to the application identification information, service component identification information, and service information in order to decode the data service data. Alternatively, such information may also prepare the operation of the application program for the data service. Furthermore, the data decoder 710 controls the demultiplexing of the system information table, which corresponds to the information table associated with the channel and events. Thereafter, an A.V PID list may be transmitted to the channel manager 707.

[213] The channel manager 707 may refer to the channel map 708 in order to transmit a request for receiving system-related information data to the data decoder 710, thereby receiving the corresponding result. In addition, the channel manager 707 may also control the channel tuning of the tuner 701. Furthermore, the channel manager 707 may directly control the demultiplexer 703, so as to set up the A/V PID, thereby controlling the audio decoder 704 and the video decoder 705. The audio decoder 704 and the video decoder 705 may respectively decode and output the audio data and video data demultiplexed from the main data packet. Alternatively, the audio decoder 704 and the video decoder 705 may respectively decode and output the audio data and video data demultiplexed from the enhanced data packet. Meanwhile, when the enhanced data include data service data, and also audio data and video data, it is apparent that the audio data and video data demultiplexed by the demultiplexer 703 are respectively decoded by the audio decoder 704 and the video decoder 705. For example, an audio-coding (AC)-3 decoding algorithm may be applied to the audio decoder 704, and a MPEG-2 decoding algorithm may be applied to the video decoder 705.

[214] Meanwhile, the native TV application manager 706 operates a native application program stored in the first memory 709, thereby performing general functions such as channel change. The native application program refers to software stored in the receiving system upon shipping of the product. More specifically, when a user request (or command) is transmitted to the receiving system through a user interface (UI), the native TV application manger 706 displays the user request on a screen through a graphic user interface (GUI), thereby responding to the user's request. The user interface receives the user request through an input device, such as a remote controller, a key pad, a jog controller, an a touch-screen provided on the screen, and then outputs the received user request to the native TV application manager 706 and the data broadcasting application manager 713. Furthermore, the native TV application manager 706 controls the channel manager 707, thereby controlling channel- associated, such as the management of the channel map 708, and controlling the data decoder 710. The native TV application manager 706 also controls the GUI of the overall receiving system, thereby storing the user request and status of the receiving system in the first memory 709 and restoring the stored information.

[215] The channel manager 707 controls the tuner 701 and the data decoder 710, so as to managing the channel map 708 so that it can respond to the channel request made by the user. More specifically, channel manager 707 sends a request to the data decoder 710 so that the tables associated with the channels that are to be tuned are parsed. The results of the parsed tables are reported to the channel manager 707 by the data decoder 710. Thereafter, based on the parsed results, the channel manager 707 updates the channel map 708 and sets up a PID in the demultiplexer 703 for demultiplexing the tables associated with the data service data from the enhanced data.

[216] The system manager 712 controls the booting of the receiving system by turning the power on or off. Then, the system manager 712 stores ROM images (including downloaded software images) in the first memory 709. More specifically, the first memory 709 stores management programs such as operating system (OS) programs required for managing the receiving system and also application program executing data service functions. The application program is a program processing the data service data stored in the second memory 711 so as to provide the user with the data service. If the data service data are stored in the second memory 711, the corresponding data service data are processed by the above-described application program or by other application programs, thereby being provided to the user. The management program and application program stored in the first memory 709 may be updated or corrected to a newly downloaded program. Furthermore, the storage of the stored management program and application program is maintained without being deleted even if the power of the system is shut down. Therefore, when the power is supplied the programs may be executed without having to be newly downloaded once again.

[217] The application program for providing data service according to the present invention may either be initially stored in the first memory 709 upon the shipping of the receiving system, or be stored in the first 709 after being downloaded. The application program for the data service (i.e., the data service providing application program) stored in the first memory 709 may also be deleted, updated, and corrected. Furthermore, the data service providing application program may be downloaded and executed along with the data service data each time the data service data are being received.

[218] When a data service request is transmitted through the user interface, the data broadcasting application manager 713 operates the corresponding application program stored in the first memory 709 so as to process the requested data, thereby providing the user with the requested data service. And, in order to provide such data service, the data broadcasting application manager 713 supports the graphic user interface (GUI). Herein, the data service may be provided in the form of text (or short message service (SMS)), voice message, still image, and moving image. The data broadcasting application manager 713 may be provided with a platform for executing the application program stored in the first memory 709. The platform may be, for example, a Java virtual machine for executing the Java program. Hereinafter, an example of the data broadcasting application manager 713 executing the data service providing application program stored in the first memory 709, so as to process the data service data stored in the second memory 711, thereby providing the user with the corresponding data service will now be described in detail.

[219] Assuming that the data service corresponds to a traffic information service, the data service according to the present invention is provided to the user of a receiving system that is not equipped with an electronic map and/or a GPS system in the form of at least one of a text (or short message service (SMS)), a voice message, a graphic message, a still image, and a moving image. In this case, is a GPS module is mounted on the receiving system shown in FIG. 19, the GPS module receives satellite signals transmitted from a plurality of low earth orbit satellites and extracts the current position (or location) information (e.g., longitude, latitude, altitude), thereby outputting the extracted information to the data broadcasting application manager 713.

[220] At this point, it is assumed that the electronic map including information on each link and nod and other diverse graphic information are stored in one of the second memory 711, the first memory 709, and another memory that is not shown. More specifically, according to the request made by the data broadcasting application manager 713, the data service data stored in the second memory 711 are read and inputted to the data broadcasting application manager 713. The data broadcasting application manager 713 translates (or deciphers) the data service data read from the second memory 711, thereby extracting the necessary information according to the contents of the message and/or a control signal.

[221] FIG. 20 illustrates a block diagram showing the structure of a digital broadcast (or television) receiving system according to another embodiment of the present invention. Referring to FIG. 20, the digital broadcast receiving system includes a tuner 801, a demodulating unit 802, a demultiplexer 803, a first descrambler 804, an audio decoder 805, a video decoder 806, a second descrambler 807, an authentication unit 808, a native TV application manager 809, a channel manager 810, a channel map 811, a first memory 812, a data decoder 813, a second memory 814, a system manager 815, a data broadcasting application manager 816, a storage controller 817, a third memory 818, and a telecommunication module 819. Herein, the third memory 818 is a mass storage device, such as a hard disk drive (HDD) or a memory chip. Also, during the description of the digital broadcast (or television or DTV) receiving system shown in FIG. 20, the components that are identical to those of the digital broadcast receiving system of FIG. 19 will be omitted for simplicity.

[222] As described above, in order to provide services for preventing illegal duplication

(or copies) or illegal viewing of the enhanced data and/or main data that are transmitted by using a broadcast network, and to provide paid broadcast services, the transmitting system may generally scramble and transmit the broadcast contents. Therefore, the receiving system needs to descrample the scrambled broadcast contents in order to provide the user with the proper broadcast contents. Furthermore, the receiving system may generally be processed with an authentication process with an anuthnetication means before the descrambling process. Hereinafter, the receiving system including an authentication means and a descrambling means according to an embodiment of the present invention will now be described in detail.

[223] According to the present invention, the receiving system may be provided with a descrambling means receiving scrambled broadcasting contents and an authentication means authenticating (or verifying) whether the receiving system is entitled to receive the descrambled contents. Hereinafter, the descrambling means will be referred to as first and second descramblers 804 and 807, and the authentication means will be referred to as an authentication unit 808. Such naming of the corresponding components is merely exemplary and is not limited to the terms suggested in the description of the present invention. For example, the units may also be referred to as a decryptor. Although FIG. 20 illustrates an example of the descramblers 804 and 807 and the authentication unit 808 being provided inside the receiving system, each of the descramblers 804 and 807 and the authentication unit 808 may also be separately provided in an internal or external module. Herein, the module may include a slot type, such as a SD or CF memory, a memory stick type, a USB type, and so on, and may be detachably fixed to the receiving system.

[224] As described above, when the authentication process is performed successfully by the authentication unit 808, the scrambled broadcasting contents are descrambled by the descramblers 804 and 807, thereby being provided to the user. At this point, a variety of the authentication method and descrambling method may be used herein. However, an agreement on each corresponding method should be made between the receiving system and the transmitting system. Hereinafter, the authentication and de- scrambling methods will now be described, and the description of identical compo nents or process steps will be omitted for simplicity.

[225] The receiving system including the authentication unit 808 and the descramblers

804 and 807 will now be described in detail. The receiving system receives the scrambled broadcasting contents through the tuner 801 and the demodulating unit 802. Then, the system manager 815 decides whether the received broadcasting contents have been scrambled. Herein, the demodulating unit 802 may be included as a demodulating means according to embodiments of the present invention as described in FIG. 16 and FIG. 18. However, the present invention is not limited to the examples given in the description set forth herein. If the system manager 815 decides that the received broadcasting contents have been scrambled, then the system manager 815 controls the system to operate the authentication unit 808. As described above, the au- thentication unit 808 performs an authentication process in order to decide whether the receiving system according to the present invention corresponds to a legitimate host entitled to receive the paid broadcasting service. Herein, the authentication process may vary in accordance with the authentication methods.

[226] For example, the authentication unit 808 may perform the authentication process by comparing an IP address of an IP datagram within the received broadcasting contents with a specific address of a corresponding host. At this point, the specific address of the corresponding receiving system (or host) may be a MAC address. More specifically, the authentication unit 808 may extract the IP address from the de- capsulated IP datagram, thereby obtaining the receiving system information that is mapped with the IP address. At this point, the receiving system should be provided, in advance, with information (e.g., a table format) that can map the IP address and the receiving system information. Accordingly, the authentication unit 808 performs the authentication process by determining the conformity between the address of the corresponding receiving system and the system information of the receiving system that is mapped with the IP address. In other words, if the authentication unit 808 determines that the two types of information conform to one another, then the authentication unit 808 determines that the receiving system is entitled to receive the corresponding broadcasting contents.

[227] In another example, standardized identification information is defined in advance by the receiving system and the transmitting system. Then, the identification information of the receiving system requesting the paid broadcasting service is transmitted by the transmitting system. Thereafter, the receiving system determines whether the received identification information conforms with its own unique identification number, so as to perform the authentication process. More specifically, the transmitting system creates a database for storing the identification information (or number) of the receiving system requesting the paid broadcasting service. Then, if the corresponding broadcasting contents are scrambled, the transmitting system includes the identification information in the EMM, which is then transmitted to the receiving system.

[228] If the corresponding broadcasting contents are scrambled, messages (e.g., entitleme nt control message (ECM), entitlement management message (EMM)), such as the CAS information, mode information, message position information, that are applied to the scrambling of the broadcasting contents are transmitted through a corresponding data header or anther data packet. The ECM may include a control word (CW) used for scrambling the broadcasting contents. At this point, the control word may be encoded with an authentication key. The EMM may include an authentication key and entitlement information of the corresponding data. Herein, the authentication key may be encoded with a receiving system-specific distribution key. In other words, assuming that the enhanced data are scrambled by using the control word, and that the authentication information and the descrambling information are transmitted from the transmitting system, the transmitting system encodes the CW with the authentication key and, then, includes the encoded CW in the entitlement control message (ECM), which is then transmitted to the receiving system. Furthermore, the transmitting system includes the authentication key used for encoding the CW and the entitlement to receive data (or services) of the receiving system (i.e., a standardized serial number of the receiving system that is entitled to receive the corresponding broadcasting service or data) in the entitlement management message (EMM), which is then transmitted to the receiving system.

[229] Accordingly, the authentication unit 808 of the receiving system extracts the identification information of the receiving system and the identification information included in the EMM of the broadcasting service that is being received. Then, the authentication unit 808 determines whether the identification information conform to each other, so as to perform the authentication process. More specifically, if the authentication unit 808 determines that the information conform to each other, then the authentication unit 808 eventually determines that the receiving system is entitled to receive the request broadcasting service.

[230] In yet another example, the authentication unit 808 of the receiving system may be detachably fixed to an external module. In this case, the receiving system is interfaced with the external module through a common interface (CI). In other words, the external module may receive the data scrambled by the receiving system through the common interface, thereby performing the descrambling process of the received data. Alternatively, the external module may also transmit only the information required for the descrambling process to the receiving system. The common interface is configured on a physical layer and at least one protocol layer. Herein, in consideration of any possible expansion of the protocol layer in a later process, the corresponding protocol layer may be configured to have at least one layer that can each provide an independent function.

[231] The external module may either consist of a memory or card having information on the key used for the scrambling process and other authentication information but not including any descrambling function, or consist of a card having the above-mentioned key information and authentication information and including the descrambling function. Both the receiving system and the external module should be authenticated in order to provide the user with the paid broadcasting service provided (or transmitted) from the transmitting system. Therefore, the transmitting system can only provide the corresponding paid broadcasting service to the authenticated pair of receiving system and external module.

[232] Additionally, an authentication process should also be performed between the receiving system and the external module through the common interface. More specifically, the module may communicate with the system manager 815 included in the receiving system through the common interface, thereby authenticating the receiving system. Alternatively, the receiving system may authenticate the module through the common interface. Furthermore, during the authentication process, the module may extract the unique ID of the receiving system and its own unique ID and transmit the extracted IDs to the transmitting system. Thus, the transmitting system may use the transmitted ID values as information determining whether to start the requested service or as payment information. Whenever necessary, the system manager 815 transmits the payment information to the remote transmitting system through the telecommunication module 819.

[233] The authentication unit 808 authenticates the corresponding receiving system and/or the external module. Then, if the authentication process is successfully completed, the authentication unit 808 certifies the corresponding receiving system and/or the external module as a legitimate system and/or module entitled to receive the requested paid broadcasting service. In addition, the authentication unit 808 may also receive authentication-associated information from a mobile telecommunications service provider to which the user of the receiving system is subscribed, instead of the transmitting system providing the requested broadcasting service. In this case, the authentication-association information may either be scrambled by the transmitting system providing the broadcasting service and, then, transmitted to the user through the mobile telecommunications service provider, or be directly scrambled and transmitted by the mobile telecommunications service provider. Once the authentication process is successfully completed by the authentication unit 808, the receiving system may descramble the scrambled broadcasting contents received from the transmitting system. At this point, the descrambling process is performed by the first and second de- scramblers 804 and 807. Herein, the first and second descramblers 804 and 807 may be included in an internal module or an external module of the receiving system.

[234] The receiving system is also provided with a common interface for communicating with the external module including the first and second descramblers 804 and 807, so as to perform the descrambling process. More specifically, the first and second de- scramblers 804 and 807 may be included in the module or in the receiving system in the form of hardware, middleware or software. Herein, the descramblers 804 and 807 may be included in any one of or both of the module and the receiving system. If the first and second descramblers 804 and 807 are provided inside the receiving system, it is advantageous to have the transmitting system (i.e., at least any one of a service provider and a broadcast station) scramble the corresponding data using the same scrambling method.

[235] Alternatively, if the first and second descramblers 804 and 807 are provided in the external module, it is advantageous to have each transmitting system scramble the corresponding data using different scrambling methods. In this case, the receiving system is not required to be provided with the descrambling algorithm corresponding to each transmitting system. Therefore, the structure and size of receiving system may be simplified and more compact. Accordingly, in this case, the external module itself may be able to provide CA functions, which are uniquely and only provided by each transmitting systems, and functions related to each service that is to be provided to the user. The common interface enables the various external modules and the system manager 815, which is included in the receiving system, to communicate with one another by a single communication method. Furthermore, since the receiving system may be operated by being connected with at least one or more modules providing different services, the receiving system may be connected to a plurality of modules and controllers.

[236] In order to maintain successful communication between the receiving system and the external module, the common interface protocol includes a function of periodically checking the status of the opposite correspondent. By using this function, the receiving system and the external module is capable of managing the status of each opposite correspondent. This function also reports the user or the transmitting system of any malfunction that may occur in any one of the receiving system and the external module and attempts the recovery of the malfunction.

[237] In yet another example, the authentication process may be performed through software. More specifically, when a memory card having CAS software downloaded, for example, and stored therein in advanced is inserted in the receiving system, the receiving system receives and loads the CAS software from the memory card so as to perform the authentication process. In this example, the CAS software is read out from the memory card and stored in the first memory 812 of the receiving system. Thereafter, the CAS software is operated in the receiving system as an application program. According to an embodiment of the present invention, the CAS software is mounted on (or stored) in a middleware platform and, then executed. A Java middleware will be given as an example of the middleware included in the present invention. Herein, the CAS software should at least include information required for the authentication process and also information required for the descrambling process.

[238] Therefore, the authentication unit 808 performs authentication processes between the transmitting system and the receiving system and also between the receiving system and the memory card. At this point, as described above, the memory card should be entitled to receive the corresponding data and should include information on a normal receiving system that can be authenticated. For example, information on the receiving system may include a unique number, such as a standardized serial number of the corresponding receiving system. Accordingly, the authentication unit 808 compares the standardized serial number included in the memory card with the unique information of the receiving system, thereby performing the authentication process between the receiving system and the memory card.

[239] If the CAS software is first executed in the Java middleware base, then the authentication between the receiving system and the memory card is performed. For example, when the unique number of the receiving system stored in the memory card conforms to the unique number of the receiving system read from the system manager 815, then the memory card is verified and determined to be a normal memory card that may be used in the receiving system. At this point, the CAS software may either be installed in the first memory 812 upon the shipping of the present invention, or be downloaded to the first memory 812 from the transmitting system or the module or memory card, as described above. Herein, the descrambling function may be operated by the data broadcasting application manger 816 as an application program.

[240] Thereafter, the CAS software parses the EMM/ECM packets outputted from the demultiplexer 803, so as to verify whether the receiving system is entitled to receive the corresponding data, thereby obtaining the information required for descrambling (i.e., the CW) and providing the obtained CW to the descramblers 804 and 807. More specifically, the CAS software operating in the Java middleware platform first reads out the unique (or serial) number of the receiving system from the corresponding receiving system and compares it with the unique number of the receiving system transmitted through the EMM, thereby verifying whether the receiving system is entitled to receive the corresponding data. Once the receiving entitlement of the receiving system is verified, the corresponding broadcasting service information transmitted to the ECM and the entitlement of receiving the corresponding broadcasting service are used to verify whether the receiving system is entitled to receive the corresponding broadcasting service. Once the receiving system is verified to be entitled to receive the corresponding broadcasting service, the authentication key transmitted to the EMM is used to decode (or decipher) the encoded CW, which is transmitted to the ECM, thereby transmitting the decoded CW to the descramblers 804 and 807. Each of the descramblers 804 and 807 uses the CW to descramble the broadcasting service.

[241] Meanwhile, the CAS software stored in the memory card may be expanded in accordance with the paid service which the broadcast station is to provide. Additionally, the CAS software may also include other additional information other than the information associated with the authentication and descrambling. Furthermore, the receiving system may download the CAS software from the transmitting system so as to upgrade (or update) the CAS software originally stored in the memory card. As described above, regardless of the type of broadcast receiving system, as long as an external memory interface is provided, the present invention may embody a CAS system that can meet the requirements of all types of memory card that may be detachably fixed to the receiving system. Thus, the present invention may realize maximum performance of the receiving system with minimum fabrication cost, wherein the receiving system may receive paid broadcasting contents such as broadcast programs, thereby acknowledging and regarding the variety of the receiving system. Moreover, since only the minimum application program interface is required to be embodied in the embodiment of the present invention, the fabrication cost may be minimized, thereby eliminating the manufacturer's dependence on CAS manufacturers. Accordingly, fabrication costs of CAS equipments and management systems may also be minimized.

[242] Meanwhile, the descramblers 804 and 807 may be included in the module either in the form of hardware or in the form of software. In this case, the scrambled data that being received are descrambled by the module and then demodulated. Also, if the scrambled data that are being received are stored in the third memory 818, the received data may be descrambled and then stored, or stored in the memory at the point of being received and then descrambled later on prior to being played (or reproduced). Thereafter, in case scramble/descramble algorithms are provided in the storage controller 817, the storage controller 817 scrambles the data that are being received once again and then stores the re-scrambled data to the third memory 818.

[243] In yet another example, the descrambled broadcasting contents (transmission of which being restricted) are transmitted through the broadcasting network. Also, information associated with the authentication and descrambling of data in order to disable the receiving restrictions of the corresponding data are transmitted and/or received through the telecommunications module 819. Thus, the receiving system is able to perform reciprocal (or two-way) communication. The receiving system may either transmit data to the telecommunication module within the transmitting system or be provided with the data from the telecommunication module within the transmitting system. Herein, the data correspond to broadcasting data that are desired to be transmitted to or from the transmitting system, and also unique information (i.e., identification information) such as a serial number of the receiving system or MAC address.

[244] The telecommunication module 819 included in the receiving system provides a protocol required for performing reciprocal (or two-way) communication between the receiving system, which does not support the reciprocal communication function, and the telecommunication module included in the transmitting system. Furthermore, the receiving system configures a protocol data unit (PDU) using a tag-length-value (TLV) coding method including the data that are to be transmitted and the unique information (or ID information). Herein, the tag field includes indexing of the corresponding PDU. The length field includes the length of the value field. And, the value field includes the actual data that are to be transmitted and the unique number {e.g., identification number) of the receiving system.

[245] The receiving system may configure a platform that is equipped with the Java platform and that is operated after downloading the Java application of the transmitting system to the receiving system through the network. In this case, a structure of downloading the PDU including the tag field arbitrarily defined by the transmitting system from a storage means included in the receiving system and then transmitting the downloaded PDU to the telecommunication module 819 may also be configured. Also, the PDU may be configured in the Java application of the receiving system and then outputted to the telecommunication module 819. The PDU may also be configured by transmitting the tag value, the actual data that are to be transmitted, the unique information of the corresponding receiving system from the Java application and by performing the TLV coding process in the receiving system. This structure is advantageous in that the firmware of the receiving system is not required to be changed even if the data (or application) desired by the transmitting system is added.

[246] The telecommunication module within the transmitting system either transmits the

PDU received from the receiving system through a wireless data network or configures the data received through the network into a PDU which is transmitted to the host. At this point, when configuring the PDU that is to be transmitted to the host, the telecommunication module within the transmitting end may include unique information {e.g., IP address) of the transmitting system which is located in a remote location. Additionally, in receiving and transmitting data through the wireless data network, the receiving system may be provided with a common interface, and also provided with a WAP, CDMA Ix EV-DO, which can be connected through a mobile telecommunication base station, such as CDMA and GSM, and also provided with a wireless LAN, mobile internet, WiBro, WiMax, which can be connected through an access point. The above-described receiving system corresponds to the system that is not equipped with a telecommunication function. However, a receiving system equipped with telecommunication function does not require the telecommunication module 819.

[247] The broadcasting data being transmitted and received through the above-described wireless data network may include data required for performing the function of limiting data reception. Meanwhile, the demultiplexer 803 receives either the real-time data outputted from the demodulating unit 802 or the data read from the third memory 818, thereby performing demultiplexing. In this embodiment of the present invention, the demultiplexer 803 performs demultiplexing on the enhanced data packet. Similar process steps have already been described earlier in the description of the present invention. Therefore, a detailed of the process of demultiplexing the enhanced data will be omitted for simplicity.

[248] The first descrambler 804 receives the demultiplexed signals from the demultiplexer 803 and then descrambles the received signals. At this point, the first de- scrambler 804 may receive the authentication result received from the authentication unit 808 and other data required for the descrambling process, so as to perform the de- scrambling process. The audio decoder 805 and the video decoder 806 receive the signals descrambled by the first descrambler 804, which are then decoded and outputted. Alternatively, if the first descrambler 804 did not perform the descrambling process, then the audio decoder 805 and the video decoder 806 directly decode and output the received signals. In this case, the decoded signals are received and then de- scrambled by the second descrambler 807 and processed accordingly.

[249] It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

[1] A method of processing a digital broadcast, comprising: grouping a plurality of consecutive enhanced data packets and determining a place of a known data sequence within the group to enable a sequence of known data to be inserted and outputted with a uniform interval in a symbol area after data interleaving; determining a known data place for memory initialization of a Trellis encoder at a beginning part of the known data sequence with reference to a data output sequence after the data interleaving, if the place of the known data is determined; determining a non- systematic RS parity place to be transmitted behind the known data for the initialization in the data output sequence after the data interleaving; and performing non-systematic RS encoding on the enhanced data packet.

[2] The method of claim 1 , the determining a place of a known data sequence further comprising: determining an MPEG header place within the enhanced data packet wherein the MPEG header place is excluded from the known data place.

[3] The method of claim 1, wherein the known data place unused for the initialization is determined to be outputted behind or ahead of the non-systematic RS parity with reference to the output data sequence after the data interleaving.

[4] The method of claim 1, wherein the interval for inserting the known data sequence within the group is an integer multiplication of a data segment length in the symbol area after the data interleaving.

[5] The method of claim 1, wherein the known data sequence inserted with the uniform interval is identical to each other.

[6] The method of claim 1, wherein if a segment sync symbol is inserted in a middle part of the known data symbol sequence inserted with the uniform interval, the segment sync symbol is always inserted in a constant place.

[7] The method of claim 1, wherein in the step determining the RS parity place, the

RS parity place is differently determined for each of the enhanced data packets.

[8] A method of processing a digital broadcast, comprising: grouping a plurality of consecutive enhanced data packets, each comprising at least one of enhanced data and known data, determining a place of a data sequence within the group to enable a sequence of known data to be inserted and outputted with a uniform interval in a symbol area after data interleaving; performing the data interleaving on an inputted enhanced data packet after inserting a plurality of non-systematic RS parities or RS parity place holders in the inputted enhanced data packet; performing memory initialization and Trellis encoding on the outputted data to output, if data interleaved and outputted is the known data and corresponds to a first part of a consecutive known data sequence; and calculating non- systematic RS parity using data within the enhanced data packet prior to the data interleaving and data for the memory initialization and then performing Trellis encoding by substituting the non-systematic RS parity or the

RS parity place holder.

[9] The method of claim 8, further comprising: performing the data interleaving on the enhanced data packet inputted in the step determining a place of a known data sequence after inserting a plurality of the

RS parity place holders; performing additional encoding on the enhanced data within the enhanced data packet interleaved and outputted only by outputting the rest of the data without performing the additional encoding thereon; and performing data deinterleaving on the enhanced data packet outputted in the above step and removing the RS parity place holder from the de-interleaved packet to output to the step.

[10] The method of claim 9, wherein the RS parity place holder is determined to be outputted behind the known data for the memory initialization with reference to an output data sequence after the data interleaving.

[11] The method of claim 9, wherein in the trellis encoding, if the data-interleaved outputted data is the known data and corresponds to the first part of the consecutive known data sequence, initialization data according to a memory state and a specific initialization state is generated and the inputted known data is then substituted by the initialization data to perform the Trellis encoding.

[12] The method of claim 9, wherein the interval for inserting the known data sequence within the group is an integer multiplication of a data segment length in the symbol area after the data interleaving.

[13] The method of claim 9, wherein the known data sequence inserted with the uniform interval is identical to each other.

[14] The method of claim 9, wherein if a segment sync symbol is inserted in a middle part of the known data symbol sequence inserted with the uniform interval, the segment sync symbol is always inserted in a constant place.

[15] A digital broadcast transmitting system comprising: an packet formatter and multiplexer grouping a plurality of consecutive enhanced data packets, each comprising at least one of enhanced data and known data, the packet formatter and multiplexer determining a place of a data sequence within the group to enable a sequence of known data to be inserted and outputted with a uniform interval in a symbol area after data interleaving, the packet formatter and multiplexer multiplexing the enhanced data packet group with a main data packet; an post-processor performing data interleaving on an output of the packet formatter and multiplexer after inserting a plurality of RS parity place holders in the output of the packet formatter and multiplexer, the post-processor performing additional encoding only if the interleaved data is the enhanced data, the postprocessor performing data deinterleaving and RS parity place holder removal; and a non- systematic RS parity place holder inserter and data interleaver performing data interleaving on an output of the post-processor by inserting a plurality of non-systematic RS parities or RS parity place holders in the output of the postprocessor, the non-systematic RS parity place holder inserter and data interleaver outputting the interleaved data for Trellis encoding.

[16] The digital broadcast transmitting system of claim 15, further comprising: an initialization enabling Trellis encoder performing memory initialization and

Trellis encoding on output data of the data interleaver to output if the output data of the data interleaver is the known data and corresponds to a first part of a consecutive known data sequence; a compatibility processor re-calculating a non-systematic RS parity from an output of the non-systematic RS parity place holder inserter and an output of the

Trellis encoder, the compatibility processor outputting the re-calculated parity to be substituted for the non- systematic RS parity or the RS parity place holder inputted to the Trellis encoder; and a transmitter inserting a sync symbol in the output of the Trellis encoder to transmit through modulation.

[17] The digital broadcast transmitting system of claim 15, wherein the RS parity place is determined to be outputted behind the known data for the memory initialization of the Trellis encoder with reference to an output data sequence of the data interleaver.

[18] The digital broadcast transmitting system of claim 15, wherein the interval for inserting the known data sequence within the group is an integer multiplication of a data segment length in the symbol area after the data interleaving.

[19] The digital broadcast transmitting system of claim 15, wherein the known data sequence inserted with the uniform interval is identical to each other.

[20] The digital broadcast transmitting system of claim 15, wherein if a segment sync symbol is inserted in a middle part of the known data symbol sequence inserted with the uniform interval, the segment sync symbol is always inserted in a constant place. [21] A digital broadcast receiving system comprising: a demodulator and equalizer receiving a signal transmitted from a digital transmitting system by tuning, the demodulator and equalizer performing demodulation and channel equalization by applying known data to the received signal; a known data detector and generator detecting the known data inserted by a transmitting side from the signal prior to the demodulation or the demodulated signal, the known data detector and generator outputting the detected known data to the demodulator and equalizer; and a non- systematic RS parity remover removing non-systematic RS parity byte inserted in a received packet if the received packet is an enhanced data packet.