Abstract:
A device and method for receiving digital broadcasting, and more particularly a device and method for providing digital multimedia services in a hybrid digital multimedia broadcasting receiver having a conditional access function. The hybrid digital broadcasting receiver includes a broadcast receiving module including a receiving section for receiving and demodulating a digital broadcasting data stream, a first demultiplexer for demultiplexing and extracting digital broadcasting data corresponding to a selected program, and a conditional access section for detecting conditional access information and decrypting the selected data using the detected information. The hybrid digital broadcasting receiver further includes a decoder module including a second demultiplexer for demultiplexing a digital multimedia data stream and a decoding section for decoding data output from the broadcast receiving module and digital multimedia data output from the second demultiplexer.

Description:
PRIORITY  
       [0001]     This application claims priority to an application entitled “Digital Multimedia Broadcasting Receiver and Method for Reproducing Digital Multimedia Data”, filed in the Korean Intellectual Property Office on Aug. 27, 2003 and assigned Serial No. 2003-59555, the contents of which are hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a device and a method for receiving digital broadcasting data, and more particularly to a device and a method for providing digital multimedia services in a digital multimedia broadcasting receiver having a conditional access function.  
         [0004]     2. Description of the Related Art  
         [0005]     In digital multimedia broadcasting (DMB), digital broadcasting data of a plurality of programs is compressed by a highly efficient compression algorithm, such as the MPEG (Moving Picture Expert Group) algorithm. The compressed data is multiplexed and broadcast as digital broadcast waves through a satellite transponder or a terrestrial repeater. In other words, digital broadcasting data is divided into video and audio data and then compressed. The compressed data is broken up into predetermined transmission units called transport packets (TP) and multiplexed into a transport stream (TS) to be transmitted. Digital broadcasting data for a plurality of programs is multiplexed in each transport stream. A user can then select a program from the multiplexed broadcasting data.  
         [0006]      FIG. 1  shows the configuration of a conventional digital multimedia broadcasting receiver. The conventional digital multimedia broadcasting receiver comprises an antenna  10 , a DMB receiving module  20 , a decoder module  30 , a display section  50  and a speaker  60 . Digital multimedia broadcasting, which is basically pay broadcasting, adopts a conditional access system (CAS) to restrict access to certain broadcasting programs. The DMB receiving module  20  and the decoder module  30  are each formed in a single chip. A conditional access section  33  provided for conditional access services is included in the decoder module  30 .  
         [0007]     In the conventional DMB receiver, digital broadcasting data received through the antenna  10  is reproduced into the original transport stream by a demodulator  21  of the DMB receiving module  20 . The reproduced transport stream is corrected by an error correcting section  23  and input to the decoder module  30 . A TS demultiplexer  31  of the decoder module  30  demultiplexes the transport stream, which includes the multiplexed digital broadcasting data for a plurality of programs. The decoder module  30  extracts transport packets that include digital broadcasting data for a program selected by the user. At this time, the digital broadcasting data is scrambled for conditional access and then transmitted. The conditional access section  33  of the decoder module  30  then receives and descrambles or decrypts the scrambled digital broadcasting data using a scrambling key generated by a smart card  40 . The decrypted digital broadcasting data is decoded by an MPEG video decoder  35  and an MPEG audio decoder  37  of the decoder module  30 , and provided to the users through the display section  50  and the speaker  60 .  
         [0008]     As described above, in digital multimedia broadcasting a plurality of programs are multiplexed into a single transport stream to be transmitted. In the conventional DMB receiver, all programs included in a transport stream received by the DMB receiving module  20  are transferred to the decoder module  30  and as described above, each module is formed in a single chip. Generally, data transmission between chips however, is made through a PAD that consumes large amounts of power. There may be some problems therefore, when the conventional DMB receiver that transfers all transport streams received by the DMB receiving module  20  to the decoder module  30  is applied directly to a mobile terminal having a limited power resource. Accordingly, it is necessary to minimize the amount of data transferred to each module of the DMB receiver and thereby reduce the power consumption.  
         [0009]     Digital data compression techniques have been rapidly developed. In the conventional DMB receiver, however, the decoder module  30  includes the conditional access section  33  as well as a decoding section for decompression. In situations when only the decoding section needs to be changed, the entire decoder module  30  including the conditional access section  33  must be replaced. Thus, it is also necessary to develop a technique for changing the decoding section independently of the conditional access section  33 .  
         [0010]     Recent development of digital technologies has driven a new trend of digital integration that eliminates the functional boundary of each digital product. In order to keep up with this new trend, studies have been made to provide mobile terminals, such as cellular phones or personal data assistant (PDA) devices, with a function for receiving digital multimedia broadcasting. However, as stated above, a conventional digital multimedia broadcasting receiver has a structure that decrypts demultiplexed digital broadcasting data at the conditional access section and then decodes the data at the decoding section. The decoder module of such a conventional DMB receiver has a problem in reproducing digital multimedia data other than digital broadcasting data. In order to install the conventional DMB receiver in a mobile terminal, an additional decoding section is required to reproduce non-scrambled multimedia data. However, a plurality of decoding sections, if provided in a mobile terminal having a limited power resource, will cause power problems and make it difficult to form a mobile terminal of small size.  
         [0011]     Accordingly, a need exists for a device and a method for providing digital multimedia services in a digital multimedia broadcasting receiver having a conditional access function, where the device minimizes the amount of data transferred and allows modifications without extensive replacements.  
       SUMMARY OF THE INVENTION  
       [0012]     Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and an object of the present invention is to provide a device and a method for reducing data traffic between each module of a digital multimedia broadcasting receiver.  
         [0013]     Another object of the present invention is to provide a device and method including a hybrid mobile terminal capable of receiving digital multimedia broadcasting and reproducing other multimedia data.  
         [0014]     Still another object of the present invention is to provide a device and method including a hybrid digital multimedia broadcasting receiver capable of providing various multimedia services.  
         [0015]     In order to accomplish the above objects, a device and method including a hybrid digital broadcasting receiver that is capable of reproducing digital multimedia data is provided in accordance with an embodiment of the present invention, which includes a broadcast receiving module and a decoder module, wherein the broadcast receiving module comprises: a receiving section for receiving and demodulating a digital broadcasting data stream into which a plurality of compressively encoded and scrambled programs are multiplexed and transmitted; a first demultiplexer for demultiplexing the demodulated digital broadcasting data stream and extracting digital broadcasting data corresponding to a program selected by a user; and a conditional access section for detecting conditional access information and decrypting the selected digital broadcasting data using the detected information. The decoder module comprises: a second demultiplexer for demultiplexing a digital multimedia data stream into which a plurality of compressively encoded digital multimedia data are multiplexed; and a decoding section for decoding digital broadcasting data output from the broadcast receiving module and digital multimedia data output from the second demultiplexer.  
         [0016]     A hybrid multimedia broadcasting receiver is also provided in accordance with an embodiment of the present invention which comprises: a receiving section for receiving a digital broadcasting data stream into which digital broadcasting data packets and conditional access information packets for a plurality of programs are multiplexed and transmitted; a first demultiplexer for separating the conditional access information packets and digital broadcasting data packets for a program selected by a user from the received digital broadcasting data stream; and a conditional access section for detecting conditional access information from the conditional access information packets and decrypting the separated digital broadcasting data packets using the conditional access information. The hybrid multimedia broadcasting receiver further comprises a second demultiplexer for receiving a digital multimedia data stream into which compressively encoded audio packets and video packets are multiplexed and separating the audio packets and the video packets from the digital multimedia data stream; and a decoding section for decoding digital broadcasting data packets output from the conditional access section and audio packets and video packets output from the second demultiplexer, wherein the receiving section, first demultiplexer and conditional access section are formed in a first integrated circuit chip while the second demultiplexer and decoding section are formed in a second integrated circuit chip.  
         [0017]     A device for processing digital broadcasting data is also provided in accordance with an embodiment of the present invention, which includes: a receiving section for receiving and demodulating a digital broadcasting data stream into which digital broadcasting data packets and conditional access information packets for a plurality of programs are multiplexed and transferred; an error correcting section for correcting an error in the demodulated digital broadcasting data stream; a demultiplexer for separating the conditional access information packets and digital broadcasting data packets for a program selected by a user from the demodulated digital broadcasting data stream; and a conditional access section for detecting conditional access information from the conditional access information packets and decrypting the separated digital broadcasting data packets using the conditional access information, wherein the device is formed in a single integrated circuit chip.  
         [0018]     Further, in order to accomplish the above objects, a method is provided in accordance with an embodiment of the present invention for providing digital multimedia services in a hybrid digital broadcasting receiver which includes a broadcast receiving module for processing digital broadcasting data and a decoder module for processing compressively encoded digital data. The method comprises the steps of: receiving at the broadcast receiving module a digital broadcasting data stream into which a plurality of scrambled programs and conditional access information are multiplexed and transferred; separating the conditional access information and digital broadcasting data for a program selected by a user from the digital broadcasting data stream received at the broadcast receiving module and decrypting the separated digital broadcasting data using the conditional access information; decoding the digital broadcasting data input from the broadcast receiving module at the decoder module; receiving a digital multimedia data stream into which compressively encoded audio data and video data are multiplexed at the decoder module; and demultiplexing the digital multimedia data stream at the decoder module to separate the audio data and the video data, and decoding the separated audio data and video data. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     The above and other objects, 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:  
         [0020]      FIG. 1  is a block diagram showing an example configuration of a conventional digital multimedia broadcasting receiver;  
         [0021]      FIG. 2  is a block diagram showing an example configuration of a hybrid digital multimedia broadcasting receiver in accordance with an embodiment of the present invention; and  
         [0022]      FIG. 3  is a flow chart showing a process of reproducing digital multimedia data in a hybrid digital multimedia broadcasting receiver in accordance with an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]     Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same element, although depicted in different drawings, will be designated by the same reference numeral or character. Also, in the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.  
         [0024]      FIG. 2  is a block diagram showing an example configuration of a hybrid digital multimedia broadcasting receiver according to an embodiment of the present invention. Hereinafter, the configuration and operation of the hybrid digital multimedia broadcasting receiver will be described in detail with reference to  FIG. 2 .  
         [0025]     The hybrid digital multimedia broadcasting receiver of  FIG. 2  comprises an antenna  210 , a broadcast receiving module  220 , a decoder module  230 , a multimedia module  260 , a display section  241  and a speaker  243 .  
         [0026]     The antenna  210  receives digital broadcast waves in which digital broadcasting data for a plurality of programs are multiplexed and transmitted. The digital broadcasting data is compressively encoded. The digital broadcasting data includes at least one of video data, audio data and additional data, which are broken up into predetermined transmission units called packets. The video data and the audio data are compressively encoded according to a conventional compression algorithm, such as H.264 (MPEG4 p.10) or MPEG4 AAC. The additional data includes image data and text data, such as caption relating to speech data. The divided transport packets are scrambled using a scrambling key for conditional access and multiplexed into a single digital broadcasting data stream, i.e., a transport stream.  
         [0027]     The broadcast receiving module  220  includes a demodulator  221 , an error correcting section  223 , a TS demultiplexer  225  and a conditional access section  227 . The broadcast receiving module  220  separates a transport stream of digital broadcasting data corresponding to a program selected by the user from the digital broadcasting data received through the antenna  210 . The broadcast receiving module  225  decrypts the scrambled digital broadcasting data and outputs the decrypted data to the decoder module  230  via an interface (not shown).  
         [0028]     The demodulator  221  amplifies digital broadcast waves received through the antenna  210 . After frequency conversion, the demodulator  221  shapes and demodulates the signal waveforms to reproduce the original transport streams. Also, the demodulator  221  extracts a transport stream of a particular channel on which a program selected by the user is broadcast from the demodulated transport streams, and outputs the extracted transport stream to the error correcting section  223 . The error correcting section  223  corrects any signal error in the transport stream.  
         [0029]     The TS demultiplexer  225  includes a section filter. The TS demultiplexer  225  demultiplexes the transport stream and separates transport packets of digital broadcasting data corresponding to the selected program. The separated packets include at least one of audio data, video data and additional data according to the selected program. The conditional access section  227  includes a descrambler  228  and a packet filter  229 . The conditional access section  227  decrypts the digital broadcasting data using a scrambling key generated by a smart card  250 . The operation performed in the broadcast receiving module  220  will be described in greater detail below with reference to  FIG. 3 .  
         [0030]     The decoder module  230  includes a TS demultiplexer  231 , a video decoder  233  and an audio decoder  235 . Although not shown in the drawings, an additional data decoder may also be included in the decoder module  230 . The operation of the TS demultiplexer  231  is similar to that performed by the TS demultiplexer  225  of the broadcast receiving module  220 . The TS demultiplexer  231  demultiplexes the multiplexed compressively encoded video data and audio data in the digital multimedia data stream. However, the TS demultiplexer  231  of the decoder module  230  is distinguished from the TS demultiplexer  225  of the broadcast receiving module  220  in that the TS demultiplexer  231  supports reproduction of various digital multimedia data other than digital broadcasting data.  
         [0031]     The digital multimedia data stream is supplied from the multimedia module  260 . Although the embodiments of the present invention described herein are based on the assumption that the multimedia module  260  includes a CDMA receiving module  261 , a multimedia game module  263  and a digital music module  265 , the multimedia module  260  can be modified to exclude a certain module or include any other module for providing digital multimedia services. The CDMA module  261  provides data, such as Music On Demand (MOD) or Video On Demand (VOD), received via a mobile communication network. The multimedia game module  263  provides multimedia game data. The digital music module  265  provides digital music data useful for music devices, such as singing machines.  
         [0032]     The video decoder  233  and the audio decoder  235  decode the data output from the TS demultiplexer  231  and that output from the broadcast receiving module  220 , and outputs the decoded data to the display section  241  and the speaker  243 , respectively. The smart card  250  stores data and programs for decrypting the conditional access code. The smart card  250  receives and transmits data to and from the conditional access section  227  through a smart card interface, which is not shown in the drawings.  
         [0033]      FIG. 3  is a flow chart showing a process of reproducing digital multimedia data in a hybrid digital multimedia broadcasting receiver in accordance with an embodiment of the present invention. Hereinafter, a method for providing various digital multimedia services, including digital broadcasting, in the digital multimedia broadcasting receiver will be described in greater detail with reference to  FIGS. 2 and 3 .  
         [0034]     At step  301 , the DMB receiver determines whether there is a request for receiving digital multimedia broadcasting from the user. If there is such a request, the DMB receiver will proceed with step  303 . At step  303 , the DMB receiver drives the broadcast receiving module  220  for processing digital broadcasting data and proceeds with step  305 .  
         [0035]     At step  305 , the DMB receiver receives digital broadcast waves through the antenna  210 . The demodulator  221  amplifies the digital broadcast waves. After frequency conversion, the demodulator  221  shapes and demodulates signal waveforms to reproduce the original transport streams. The demodulator  221  extracts a transport stream of a particular channel on which a program selected by the user is delivered, and outputs the extracted transport stream to the error correcting section  223 . At step  307 , the error correcting section  223  corrects any signal error in the reproduced transport stream.  
         [0036]     At step  309 , the TS demultiplexer  225  separates Program Association Table (PAT) transport packets from the error-corrected transport stream and analyzes the packets. The PAT containing a complete list of all program control information is almost always carried in packets with a packet ID (PID)=0. At step  311 , the TS demultiplexer  225  detects PIDs of the Program Map Table (PMT) corresponding to the program selected by the user. At step  313 , the TS demultiplexer  225  separates transport packets corresponding to the selected program from the transport stream using the detected PIDs, and provides the separated packets to the conditional access section  227 . These transport packets corresponding to the selected program are the digital broadcasting data that constructs the selected program, and are scrambled for the purpose of conditional access.  
         [0037]     A scrambling key for descrambling the scrambled transport packets is generated using the Entitlement Control Message (ECM) and the Entitlement Management Message (EMM). The ECM consists of program attribute information and ECM packets, while the EMM consists of contract information of each user and EMM packets. The ECM and EMM messages are transmitted together with scrambled transport packets of video and audio data.  
         [0038]     Steps  315  to  325  are provided for generating a scrambling key, and will be described in greater detail below. At step  315 , the TS demultiplexer  225  extracts PIDs of Conditional Access Table (CAT) packets and PMT packets containing ECM information. At step  317 , the TS demultiplexer  225  separates the CAT packets and the PMT packets from the transport stream using the PIDs and analyzes the separated packets. At step  319 , the TS demultiplexer  225  detects PIDs of EMM and ECM packets from the CAT and PMT packets. At step  321 , the PIDs of the EMM and ECM packets are sent to the conditional access section  227  and set to values of a packet filter  229 . The packet filter  229  detects EMM and ECM packets among the transport packets sent from the TS demultiplexer  225 , and extracts the EMM and ECM information.  
         [0039]     At step  323 , the extracted EMM and ECM information is transferred to the smart card  250 . At step  325 , the smart card  250  generates a scrambling key based on the EMM and ECM information and sends the scrambling key to the conditional access section  227 .  
         [0040]     At step  327 , the descrambler  228  of the conditional access section  227  decrypts the conditional access code of the transport packets corresponding to the selected program using the scrambling key input from the smart card  250 . The decrypted digital broadcasting data is then input to the decoder module  230 .  
         [0041]     At step  329 , the video decoder  233  and audio decoder  235  of the decoder module  230  decode video data and audio data of the digital broadcasting data, respectively. At step  331 , the decoded video data and audio data are output through the display section  241  and the speaker  243 , respectively. If additional data, such as caption data is included in the digital broadcasting data, it will be decoded by an additional data decoder (not shown) and output through the display section  241 .  
         [0042]     If there is no request for receiving digital multimedia broadcasting from the user at step  301 , the DMB receiver will proceed with step  333  and will determine whether there is a request to reproduce digital multimedia data. In other words, the TS demultiplexer  231  of the decoder module  230  determines whether digital multimedia data has been input from the multimedia module  260 . Although the embodiments above describe a device and method in which the DMB receiver determines whether the receiver is requested to reproduce digital multimedia data after determining whether the receiver is requested to receive digital multimedia broadcasting, it will be obvious to one skilled in the art that the order of determining the two requests can be reversed. Also, it is possible to modify the DMB receiver to receive digital multimedia broadcasting and reproduce digital multimedia data independently and simultaneously.  
         [0043]     If it is determined that digital multimedia data has not been input at step  333 , the DMB receiver will return to the waiting mode of step  301 . If digital multimedia data is input, the DMB receiver will proceed with step  335 . At step  335 , the TS demultiplexer  231  demultiplexes the input data and separates the multiplexed video and audio data. Through steps  329  to  331 , the separated data will be provided to the user.  
         [0044]     Although a preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims, including the full scope of equivalents thereof.  
         [0045]     As described above, the present invention can provide digital multimedia broadcasting and other digital multimedia services in a single terminal. Also, various practical multimedia functions can be easily added to the hybrid multimedia broadcasting receiver in accordance with the embodiments of the present invention. It is possible to produce a small-sized hybrid multimedia broadcasting receiver by minimizing the number of elements added to support practical multimedia services. In addition, the present invention can reduce power consumption by reducing data traffic between chips.