CLAIM OF PRIORITY 
     This application claims the benefit of the earlier filing date, under 35 U.S.C. 119(a), to that patent application entitled “Digital Broadcast Transmission/Reception Apparatus for Rapid Channel Change” filed in the Korean Intellectual Property Office on Dec. 5, 2005 and assigned Serial No. 2005-117723, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates digital multimedia broadcast, and more particularly to a digital broadcast transmission/reception apparatus with rapid channel change through reduction of the parsing time for program specific information (PSI). 
     2. Description of the Related Art 
     An analog television displays a corresponding broadcast of a channel when a physical channel change occurs, but a digital television requires a delay of at least two seconds until it displays a corresponding broadcast of a channel when a physical channel change occurs. Such a time delay in a channel change is regarded as a weak point of digital broadcasting, as compared with analog broadcasting. 
     This delay time in the digital television is the sum of channel tuning time, PSI parsing time, and Audio/Video (A/V) decoding time. The first factor “channel tuning time” is determined according to the tuning speed of a physical tuner, the second factor “parsing time” is determined according to a parsing algorithm, and the third factor “A/V decoding time” is determined according to the setup of a physical buffer Video Buffering Verifier (VBV) and I(Intra)-frame detection. 
       FIG. 1  is a block diagram illustrating the construction of a PSI parsing unit in a conventional digital broadcasting reception apparatus. 
     According to the conventional digital broadcasting reception apparatus, the PSI parsing unit  100  extracts a Program Association Table (PAT)  103  and a Program Map Table (PMT  105 ) by demultiplexing a digital broadcast received through a tuner  101 , and transmits a relevant elementary stream (ES) to a decoder  107 , thereby providing a digital broadcast to the user. 
     In more detail, the PSI parsing unit  100  first extracts the PAT  103  through a first demultiplexer  102 , and demultiplexes the output of the first demultiplexer  102  in a second demultiplexer  104  using the information of the PAT  103 , thereby extracting the PMT  105 . Then, the PSI parsing unit  100  extracts an elementary stream (ES) in a third demultiplexer  106  using the PMT  105 . Such PSI parsing causes a time delay upon a channel change, so research is being conducted to reduce such a PSI parsing time. 
     Generally, in a digital television, when a physical channel change occurs, PAT parsing, PMT parsing, and filtering procedures are sequentially performed before a corresponding digital broadcast is displayed. This means that a channel change time is extended. Various methods have been proposed in order to reduce the PSI parsing time. However, it is not easy to apply such methods due to several reasons; for example, these methods may require additional hardware. 
     There has been proposed a method for improving a channel change speed in a digital broadcasting receiver (set-top box), in which a tuner is additionally installed in a reception terminal so as to scan all channels and to store PSI obtained through the scanning in a memory. However, this method has a problem in that a separate tuner must be installed in the reception terminal. Another proposed method for removing the searching time for a PSI packet in digital multimedia broadcasting (DMB), in which a transport stream (TS) is buffered in a reception terminal during about two seconds, and then a PAT and a PMT included in the buffered data are parsed, thereby reducing a delay time. However, since this method unnecessarily buffers the stream in the reception terminal during two seconds, a longer time delay may be incurred, as compared with a general algorithm which parses PSI without such a buffering process. 
     Third, there has been proposed a method for reducing an initial starting time of a DMB terminal through PMT search, in which a search is performed in order to find a TS whose header and payload includes predetermined bits identical to those of a PMT. Although this method may have an effect in a single channel for PMT, this method requires longer waiting time and PAT parsing time for all channels under a multi-channel environment. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art and provides additional advantages, by providing a digital broadcasting transmission/reception apparatus for rapid channel change, in which a digital broadcasting transmission terminal transmits packet identifier (PID) information of all channels together with a transport stream (TS) for each channel based on the fact that the PID of digital broadcast streams of each broadcasting station are constantly maintained, thereby solving the longer channel change time as compared to that of analog televisions. 
     To accomplish this object, in accordance with one aspect of the present invention, there is provided a digital broadcasting transmission apparatus for rapid channel change to an A/V stream of a predetermined channel, the apparatus including a program specific information (PSI) generation unit for generating PSI of the A/V stream, a PSI length detection unit for detecting a length of the PSI generated by the PSI generation unit, a channel information (CI) generation unit for generating CI which includes PSI of all digital broadcasting channels input to the digital broadcasting transmission apparatus, a CI insertion unit for dividing and inserting the CI generated by the CI generation unit into a PSI transmission area generated by the PSI generation unit according to the length information detected by the PSI length detection unit and a transport stream (TS) multiplexing unit for multiplexing and outputting the A/V stream and an output of the CI insertion unit. 
     In accordance with another aspect of the present invention, there is provided a digital broadcasting reception apparatus for rapid channel change in a digital broadcasting system in which channel information (CI) is transmitted, the apparatus including a tuner for receiving a digital broadcasting transport stream (TS) transmitted from a transmission apparatus; a CI extraction unit for extracting the CI from the digital broadcasting TS received through the tuner; a CI parser for parsing the CI extracted by the CI extraction unit, a program specific information (PSI) parser for receiving a remaining information, except for the CI extracted by the CI extraction unit, parsing PSI, and outputting an A/V stream; a CI processing unit for processing the CI parsed by the CI parser; and a storage unit for storing the CI processed by the CI processing unit as a PSI lookup table, wherein the CI processing unit retrieves the lookup table stored in the storage unit and transmits the lookup table to the PSI parser when there is a physical channel change through the tuner. 
     In accordance with still another aspect of the present invention, there is provided a digital broadcasting transmission apparatus for rapid channel change to an A/V stream of a predetermined channel, the apparatus including a program specific information (PSI) generation unit for generating PSI of the A/V stream, a channel information (CI) generation unit for generating CI which includes PSI of all digital broadcasting channels input to the digital broadcasting transmission apparatus, a CI insertion unit for inserting the CI generated by the CI generation unit, a CI transport stream (CI TS) generation unit for generating an independent transmission channel from the CI inserted through the CI insertion unit, and a TS multiplexing unit for multiplexing and transmitting outputs of the A/V stream, the PSI generation unit, and the CI TS generation unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  presents a block diagram illustrating the construction of a PSI parsing unit in a conventional digital broadcasting reception apparatus; 
         FIGS. 2A and 2B  represent block diagrams illustrating the construction of a digital broadcasting transmission/reception apparatus for rapid channel change according to a first embodiment of the present invention; 
         FIGS. 3A to 3D  represent block diagrams for explaining CI insertion in a digital broadcasting transmission apparatus for rapid channel change according to the first embodiment of the present invention; 
         FIG. 4  represents a view illustrating a PID lookup table stored in the storage unit of the digital broadcasting reception apparatus for rapid channel change according to the first embodiment of the present invention; 
         FIG. 5  represents a view for explaining the difference between the channel change method of the present invention and the conventional method employing a decoding scheme; and 
         FIGS. 6A and 6B  represents block diagrams illustrating the construction of a digital broadcasting transmission/reception apparatus for rapid channel change according to a second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. For the purposes of clarity and simplicity, a detailed description of known functions and configurations incorporated herein will be omitted when it may obscure the subject matter of the present invention. 
     The present invention proposes a method for reducing a time delay caused in a program specific information (PSI) parsing procedure in such a manner that a digital broadcasting transmission terminal inserts packet identifier (PID) information of all transmission channels into a transmission stream (TS) for each channel, and a reception terminal parses and stores the PID information of all channels in a storage unit, thereby reducing a time period for a PSI parsing in the future. 
       FIGS. 2A and 2B  represent block diagrams illustrating the construction of a digital broadcasting transmission and reception apparatus, respectively, for rapid channel change according to a first embodiment of the present invention. 
       FIG. 2A  represents a block diagram illustrating the construction of the digital broadcasting transmission apparatus for rapid channel change according to the first embodiment of the present invention. The digital broadcasting transmission apparatus receives an A/V stream  201  of a predetermined channel, a PSI generation unit  202 , a PSI length detection unit  203 , a channel information (CI) generation unit  204 , a CI insertion unit  205 , and a TS multiplexing unit  206 . The PSI generation unit  202  generates PSI of the A/V stream  201 , and the PSI length detection unit  203  detects the length of the PSI generated by the PSI generation unit  202 . The CI generation unit  204  generates CI including PSI of all digital broadcasting channels which are input to the digital broadcasting transmission apparatus. The CI insertion unit  205  divides and inserts the CI generated by the CI generation unit  204  into a PSI transmission area generated by the PSI generation unit  202 , according to the length information detected by the PSI length detection unit  203 . The TS multiplexing unit  206  multiplexes the A/V stream  201  and the CI inserted by the CI insertion unit  205 , and transmits the multiplexed data. 
     In more detail, the CI generation unit  204  forms CI by using elementary stream information of all channels which are received by the transmission apparatus. 
     In this case, the CI has a frame structure as shown in Table 1. 
     
       
         
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                 The 
                   
                   
                 Packet  
                 The 
                   
                   
               
               
                   
                 Number 
                   
                   
                 Clock 
                 Number of 
                   
                   
               
               
                 Channel 
                 of 
                 Program 
                 PMT 
                 Reference_ 
                 Elementary 
                 Type of 
                 Elementary 
               
               
                 ID 
                 Programs 
                 Number 
                 PID 
                 (PCR)_PID 
                 PIDs 
                 Stream 
                 PID 
               
               
                   
               
             
             
               
                 5 bits 
                 3 bits 
                 16 bits 
                 13 bits 
                 13 bits 
                 2 bits 
                 8 bits 
                 13 bits 
               
               
                 (32 IDs) 
                 (8 programs) 
                   
                   
                   
                 (4 PIDs) 
               
               
                   
               
             
          
         
       
     
     Herein, “Channel ID” represents an ID of a physical channel. “The Number of Programs” represents the number of programs included in one physical channel, and “Program Number” represents an identifier for each program. “PMT PID” and “PCR PID” represent PSI of each program. “The Number of Elementary PIDs” represents the number of elementary streams included in each program, the type and PID information of each elementary stream are represented using “Type of Stream” and “Elementary PID” fields, respectively. 
     Herein, data of three fields, including “Channel ID”, “The Number of Programs”, and “The Number of Elementary PIDs”, are information additionally inserted for CI, and data of the remaining five fields are information inserted into a program association table (PAT) and a program map table (PMT). 
     Therefore, for example, when a channel is formed as shown in Table 2, CI of the channel is generated as Table 3. 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                 Program 
                   
                   
                 Type of 
                 Elementary 
               
               
                   
                 Number 
                 PMT PID 
                 PCR PID 
                 Stream 
                 PID 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Ch 1 
                 1 
                 10 
                 11 
                 2 
                 11 
               
               
                   
                   
                   
                   
                 129 
                 12 
               
               
                   
                 2 
                 20 
                 129 
                 129 
                 21 
               
               
                 Ch 2 
                 3 
                 30 
                 31 
                 2 
                 31 
               
               
                   
                   
                   
                   
                 129 
                 32 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
             
             
               
                 1 
                 2 
                 1 
                 10 
                 11 
                 2 
                 2 
                 11 
                 129 
                 12 
                 2 
                 20 
                 129 
               
               
                 1 
                 129 
                 21 
                 2 
                 1 
                 3 
                 30 
                 31 
                 2 
                 2 
                 31 
                 129 
                 32 
               
               
                   
               
             
          
         
       
     
     CI generated from Table 2 will now be described with reference to Tables 2 and 3. First, a first number “1” in CI of Table 3 represents a channel ID. That is, the first number “1” means “Ch 1” of Table 2. A second number “2” in Table 3 represents the number of programs, and means that the “Ch 1” includes two programs, which is shown in Table 2. Next, program number “1” is entered, and then PMT ND “10” and PCR PID “11” are sequentially expressed. Then, the number of, elementary PIDs included in program number “1” is entered as “2”, and the stream type and PID of each elementary are expressed as “2” and “11”, and as “129” and “12”. 
     Next, program number “2” is entered, and then PMT PID “20” and PCR PID “129” are sequentially expressed. Then, the number of elementary PIDs included in program number “1” is entered as “1”, and the stream type and PID of the elementary are expressed as “129” and ‘21”. 
     After information about the first channel ID has been expressed as described above, information about a second channel ID is entered in the same manner. 
     For reference, in the case of digital multimedia broadcasting (DMB), each channel for satellite and terrestrial waves are formed as shown in Table 4. 
     
       
         
               
               
               
             
               
               
               
             
           
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                 Satellite DMB 
                 Terrestrial DMB 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Channel ID 
                 27 
                 6 
               
               
                 The Number of Programs 
                  1 
                 3~7  
               
               
                 The Number of Elementary PIDs 
                 1~27 
                 1~27 
               
               
                 Maximum Size of CI 
                 2538 bits 
                 3660 bits 
               
               
                 Minimum Size of CI 
                 2334 bits 
                 2063 bits 
               
               
                   
               
             
          
         
       
     
     “Channel ID”, “The Number of Programs”, and “The Number of Elementary PIDs”, which are additionally included for flexible construction of CI, are formed with five, three, and two bits, respectively, so as to express maximum of 27, 7, and 2 for the number of IDs, programs, and PIDs, respectively. When the channel property is changed, the above bit numbers may be changed. 
     The maximum size of CI is calculated by the maximum number of elementary PIDs forming the PMT and the maximum number of PMTs forming the PAT, and the minimum size of CI is a number obtained by considering both 27 satellite DMB channels and 6 terrestrial DMB channels. Therefore, it can be noted that 292 bytes for satellite DMB and 258 bytes for terrestrial DMB are enough to express data for all channel information in the current DMB system. 
     The PSI length detection unit  203  receives a PSI TS generated by the PSI generation unit  202 , and extracts a length value of valid data among all 188 bytes by using the value of an area length field in the PSI area. Then, the PSI length detection unit  203  provides the extracted length value of valid data to the CI insertion unit  205 . 
     The CI insertion unit  205  divides CI generated by the CI generation unit  204  into proper sizes by using the length value of valid data provided from the PSI length detection unit  203 , and inserts the divided CI into the PSI TS. 
       FIGS. 3A to 3D  are block diagrams for explaining CI insertion in a digital broadcasting transmission apparatus for rapid channel change according to the first embodiment of the present invention. 
     When there is a TS including different PSI area data  302  and  305 , as shown in  FIG. 3A , the CI insertion unit  205  divides CI  307 , generated as shown in  FIG. 3B , into two pieces of data  307 - 1  and  307 - 2 , as shown in  FIG. 3C , based on length information detected through the PSI length detection unit  203 , and inserts the divided CI data  307 - 1  and  307 - 2  into invalid areas  303  and  306  of the PSI TS, as shown in  FIG. 3D , respectively, so as to transmit the divided CI data  307 - 1  and  307 - 2  with the PSI TS. 
       FIG. 2B  is a block diagram illustrating the construction of the digital broadcasting reception apparatus for rapid channel change according to the first embodiment of the present invention. The digital broadcasting reception apparatus includes a CI extraction unit  207 , a CI parser  208 , a PSI parser  211 , a CI processing unit  209 , and a storage unit  210 . The CI extraction unit  207  receives a digital broadcasting TS transmitted from the transmission apparatus and extracts CI from the digital broadcasting TS. The CI parser  208  parses the CI extracted by the CI extraction unit  207 . The PSI parser  211  receives the remaining information, except for the CI extracted by the CI extraction unit  207 , parses PSI, and outputs an A/V stream. The CI processing unit  209  processes the CI parsed by the CI parser  208 . The storage unit  210  stores the CI processed by the CI processing unit  209 , so as to transmit the CI to the PSI parser  211  through the CI processing unit  209  when a physical channel change occurs. 
     That is, the CI extraction unit  207  detects the length of PSI data, in a manner similar to that of the PSI length detection unit  203 , and extracts and transmits the remaining portion, except for the data of the detected length, to the CI parser  208 . 
     Then, the CI parser  208  analyzes CI and stores PID information of all channels in the storage unit  210  through the CI processing unit  209 . That is, a PID lookup table is formed. 
       FIG. 4  is a view illustrating a PID lookup table stored in the storage unit of the digital broadcasting reception apparatus for rapid channel change according to the first embodiment of the present invention. 
     When PID information has been stored as shown in  FIG. 4 , PID information to be filtered is sent to the PSI parser  211  as soon as a tuner of the reception apparatus operates, so that the PSI parsing time becomes substantially near to zero, thereby achieving rapid channel change. 
       FIG. 5  is a view explaining the difference between the channel change method of the present invention and the conventional method employing a decoding scheme. 
     According to the present invention, as soon as a physical channel change command is issued through a tuner, the PID lookup table stored in the storage unit  210  is read, and the value of a PID to be filtered is transmitted to the TS demultiplexing unit, thereby requiring a much shorter time period than the conventional method employing a decoding scheme, so that a time period required for a PSI parsing becomes close to zero. 
       FIGS. 6A and 6B  represent block diagrams illustrating the construction of a digital broadcasting transmission and reception apparatus, respectively, for rapid channel change according to a second embodiment of the present invention. 
       FIG. 6A  is a block diagram illustrating the construction of the digital broadcasting transmission apparatus for rapid channel change according to the second embodiment of the present invention. The digital broadcasting transmission apparatus for transmitting an A/V stream  601  of a predetermined channel includes a PSI generation unit  602 , a channel information (CI) generation unit  603 , a CI insertion unit  604 , a CI TS generation unit  605 , and a TS multiplexing unit  606 . The PSI generation unit  602  generates PSI of the A/V stream  601 , and the CI generation unit  603  generates CI including PSI of all digital broadcasting channels which are input to the digital broadcasting transmission apparatus. The CI insertion unit  604  inserts the CI generated by the CI generation unit  603 , and the CI TS generation unit  605  generates an independent channel from the CI inserted by the CI insertion unit  604 . The TS multiplexing unit  606  multiplexes and transmits the outputs of the A/V stream  601 , the PSI generation unit  602 , and the CI TS generation unit  605 . 
     According the second embodiment of the present invention, CI can carry information about all channels as an independent channel, instead of an invalid empty space in a PSI TS. 
     In this case, the CI is allocated with a separate PID, and a reception apparatus senses the corresponding PID and parses the CI stored in a space except for a TS header. Herein, the reception apparatus has the same construction as that shown in  FIG. 2B . 
     As described above, according to the present invention, in order to solve the weak point of a digital television, which requires a longer channel change time than that of an analog television, the digital broadcasting transmission terminal transmits PID information of all channels together with a TS for each channel based on the fact that the PID of digital broadcast streams of each broadcasting station are constantly maintained, so that it is possible to rapidly achieve a channel change. 
     While the present invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Accordingly, the scope of the invention is not to be limited by the above embodiments but by the claims and the equivalents thereof.
Disclosed is a digital broadcasting transmission apparatus for rapid channel change to an A/V stream of a predetermined channel, the apparatus including a program specific information (PSI) generation unit for generating PSI of the A/V stream, a PSI length detection unit for detecting a length of the PSI generated by the PSI generation unit; a channel information (CI) generation unit for generating CI which includes PSI of all digital broadcasting channels input to the digital broadcasting transmission apparatus, a CI insertion unit for dividing and inserting the CI generated by the CI generation unit into a PSI transmission area generated by the PSI generation unit, according to the length information detected by the PSI length detection unit, and a transport stream (TS) multiplexing unit for multiplexing and outputting the A/V stream and an output of the CI insertion unit.