Abstract:
A system and method are provided for providing a broadcast service (BCAST) in a mobile broadcast system. The system and method include a file application function (FA) that provides a file attribute related to the broadcast service, receives at least one file to be provided to at least one terminal and attribute information for the file, and delivers the received file and attribute information to a file delivery function (FD) in a BCAST service distribution/adaptation (BSD/A). The FD generates at least one bundle of files using the at least one received file based on service configuration information of a file transmitted from a BCAST subscription management (BSM) that manages subscriber information of the terminal, and generates a BCAST file including the at least one file or one bundle of files. The FD negotiates with a BDS service distribution (BDS-SD) that controls the BDS and the interaction network, using configuration information for the BCAST file to set up a bearer for delivering the generated BCAST file. After completion of setting up the bearer, the FD delivers the BCAST file to a terminal subscribed to the broadcast service.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit under 35 U.S.C. §119(a) of Korean Patent Application No. 10-2005-0027838 entitled “File Distribution Method and Apparatus in a Mobile Broadcast System”, filed in the Korean Intellectual Property Office on Apr. 2, 2005, the entire disclosure of which is hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention:  
         [0003]     The present invention relates generally to a mobile broadcast system supporting Broadcast Service (BCAST). In particular, the present invention relates to a method and apparatus for simultaneously delivering a file or a bundle of files to a plurality of terminals in a mobile broadcast system.  
         [0004]     2. Description of the Related Art:  
         [0005]     Due to recent developments of communication and broadcast technologies, broadcast systems or mobile communication systems attempt to provide broadcast services to terminals with mobility, and there is lively discussion regarding not only common broadcast service limited to voice and image data, but also regarding service that is capable of transmitting packet data over a broadcast channel. Herein, services of the two types will be referred to as mobile broadcast service, and a system supporting mobile broadcast service will be referred to as a mobile broadcast system.  
         [0006]     The Open Mobile Alliance (OMA), an organization for studying the standard for interaction between individual mobile solutions, mainly serves to establish various application standards for mobile games, Internet services, and so forth. In particular, the Open Mobile Alliance Browser and Content Mobile Broadcast Sub Working Group (OMA BAC BCAST) among OMA working groups is studying technology for providing broadcast service using mobile terminals. Additional details of this work is described in a text entitled “Mobile Broadcast Services Architecture, Draft Version 1.0-10 March 2006”, published by the Open Mobile Alliance Ltd., 2005, the entire disclosure of which is hereby incorporated by reference.  
         [0007]     In the mobile broadcast system under discussion in the OMA, the step in which mobile broadcast service is achieved may include processes of discovering services by mobile terminals for broadcast service, subscribing to the services by the mobile terminals, providing various control information to receive the services, transmitting the services, and receiving the services by the terminals. A description will now be made of the mobile broadcast system which is now under discussion in the OMA.  
         [0008]      FIG. 1  is a diagram illustrating a logical configuration of a mobile broadcast system proposed in the BCAST Working Group of the OMA. Specifically,  FIG. 1  illustrates an application layer and its lower transport layer and network layer in the mobile broadcast system.  
         [0009]     In the OMA BCAST, the technical fields and functions being discussed for mobile broadcast service include a service guide for discovering mobile broadcast service, service recovery, streaming and file distribution, service and content protection, service provisioning, interaction between a mobile broadcast network and a cellular network, and notification that is capable of indicating a start of the mobile broadcast service and a change in the mobile broadcast service. These functions are located in BCAST logical entities shown in  FIG. 1  by way of example. A description of the logical entities and interfaces shown in  FIG. 1  is made with reference to Table 1 and Table 2 below. Table 1 and Table 2 describe, by way of example, entity names and functions (or roles) of exemplary elements used in the following descriptions.  
                       TABLE 1                       No.   Entity name   Role                   102   BCAST Service   Represents the service application of           Application   the BCAST Service, such as streaming           (BSA)   audio/video or movie file download.               It encompasses the functionality of               media encoding, content protection               and interaction related to BCAST               Service. It also provides the BCAST               service attributes to the BCAST Service               Distribution/Adaptation and BCAST               Subscription Management.               It may generate charging information,               for example, according to the user               charging information that it obtains               from the BCAST subscription management               and the content creator. Legacy               mechanisms may be used for charging               information generation and delivery.       103   BCAST Service   Responsible for the aggregation and           Distribution/   delivery of BCAST Services, and performs           Adaptation   the adaptation of the BCAST Enabler           (BSD/A)   to underlying Broadcast Distribution               Systems. It provides the functionality               of File and Stream Distribution,               Service Aggregation, Service Protection,               Service Guide generation and delivery,               Notification Delivery, and the adaptation               to the underlying BDS. The functionality               of adaptation to each BDS may vary               depending on the underlying BDS.       104   BCAST   Responsible for service provisioning           Subscription   such as subscription and payment related           Management   functions, the provision of information           (BSM)   used for BCAST Service reception, and               BCAST Terminal management.               It provides the functionality of Notifi-               cation, Service Protection management,               Content Protection management, Service               Guide generation support, Terminal               Provisioning and interaction with the               BDS Service Distribution to communicate/               manage subscription information with the               Terminal.               It may send the user charging information               to the BCAST service application.       105   Terminal   The user device that receives broadcast               content as well as the BCAST service               related information, such as, service               guide, and content protection information.               The user device may support the inter-               active channel in which case it would               be able to directly communicate to the               network regarding the available services.       101   Content   Source of content, may provide support           Creation   for delivery paradigms (e.g. streaming           (CC)   servers), and provides base material               for content descriptions.       111   BDS Service   Responsible for the coordination and           Distribution   delivery of broadcast services to the               BDS for delivery to the terminal,               including file and stream distribution,               and Service Guide distribution. It may               also include key distribution, broadcast               subscription management, and accounting               functions. BDS Service Distribution may               not exist in certain BDSs. In that case               it would be considered a “Null Function”.               It works with the interactive network to               perform service discovery, BDS-specific               service protection and handles other               interaction functions. It also works with               the BDS for content delivery to the terminal.       112   Broadcast   Specific support for the distribution of           Distribution   content over the broadcast channel. This           System (BDS)   may involve the same or different radio               network from that used by the interactive               channel.       113   Interaction   Specific support for the interaction channel.           Network   This may involve the same or different               radio network from that used by the               broadcast channel.                  
 
         [0010]    
       
         
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
               
               
                   
                 Reference 
                   
               
               
                 No. 
                 point name 
                 Usage 
               
               
                   
               
             
             
               
                 121 
                 BCAST-1 
                 Content, Content attributes, notification 
               
               
                   
                   
                 event, and so forth. 
               
               
                 122 
                 BCAST-2 
                 Content-unprotected and/or content-protected 
               
               
                   
                   
                 BCAST Service, BCAST Service attributes and 
               
               
                   
                   
                 content attributes. 
               
               
                 123 
                 BCAST-3 
                 BCAST Service attributes and content attri- 
               
               
                   
                   
                 butes, User preference and subscription 
               
               
                   
                   
                 information, User request, User reporting, 
               
               
                   
                   
                 notification event and maybe user charging 
               
               
                   
                   
                 information. 
               
               
                 124 
                 BCAST-4 
                 Notification, Service Guide, fragments 
               
               
                   
                   
                 (related to provisioning, purchasing, sub- 
               
               
                   
                   
                 scription, terminal provisioning, and so 
               
               
                   
                   
                 forth), Service keys, Terminal Provisioning 
               
               
                   
                   
                 object, Terminal Provisioning message, 
               
               
                   
                   
                 Terminal management message, and so forth. 
               
               
                 125 
                 BCAST-5 
                 Unprotected and/or protected BCAST Service, 
               
               
                   
                   
                 content-unprotected and/or content-protected 
               
               
                   
                   
                 BCAST Service, BCAST Service attributes and 
               
               
                   
                   
                 content attributes. Notification, Service Guide, 
               
               
                   
                   
                 Security material, all of which are distributed 
               
               
                   
                   
                 over the Broadcast Distribution System. 
               
               
                 126 
                 BCAST-6 
                 Unprotected and/or protected BCAST Service, 
               
               
                   
                   
                 content-unprotected and/or content-protected 
               
               
                   
                   
                 BCAST Service, BCAST Service attributes and 
               
               
                   
                   
                 content attributes, Notification, Service Guide, 
               
               
                   
                   
                 Security material, terminal reports related 
               
               
                   
                   
                 to stream and file delivery, all distributed 
               
               
                   
                   
                 over the Interaction Network. 
               
               
                 127 
                 BCAST-7 
                 Service provisioning, Subscription information, 
               
               
                   
                   
                 Terminal provisioning, Security material and 
               
               
                   
                   
                 device registration. 
               
               
                 128 
                 BCAST-8 
                 User interaction, reporting, and user preference. 
               
               
                 129 
                 BDS1 
                 Unprotected and/or protected BCAST Service, 
               
               
                   
                   
                 content-unprotected and/or content-protected 
               
               
                   
                   
                 BCAST Service, BCAST Service attributes and 
               
               
                   
                   
                 content attributes, BDS-specific attributes, 
               
               
                   
                   
                 Notification and Service Guide fragments. 
               
               
                   
                   
                 Note: Service protection or Content Protection 
               
               
                   
                   
                 of RTP streams may be employed by the BDS 
               
               
                   
                   
                 itself, if available. 
               
               
                 130 
                 BDS2 
                 Service provisioning, Subscription information, 
               
               
                   
                   
                 Device management, and Security material. 
               
               
                 131 
                 X-1 
                 Reference Point between BDS Service Distri- 
               
               
                   
                   
                 bution and BDS. 
               
               
                 132 
                 X-2 
                 Reference Point between BDS Service Distri- 
               
               
                   
                   
                 bution and Interaction Network. 
               
               
                 133 
                 X-3 
                 Reference Point between BDS and Terminal. 
               
               
                 134 
                 X-4 
                 Reference Point between BDS Service Distri- 
               
               
                   
                   
                 bution and Terminal over Broadcast Channel. 
               
               
                 135 
                 X-5 
                 Reference Point between BDS Service Distri- 
               
               
                   
                   
                 bution and Terminal over Interaction Channel. 
               
               
                 136 
                 X-6 
                 Reference Point between Interaction Network 
               
               
                   
                   
                 and Terminal. 
               
               
                   
               
             
          
         
       
     
         [0011]     In the descriptions of Table 2, ‘reference point’ indicates a connection path between two particular logical entities and can have a plurality of interfaces according to its object. The interfaces are used for communication between two or more functional entities for a particular object, and message types and protocols for the object are used therefor.  
         [0012]     Among the various functions of the OMA BCAST, a File Distribution Function serves to deliver a file or a bundle of files with various media types and various encoding schemes to terminals. Although a broadcast channel is mainly used for file distribution, an interaction channel may also be used for file distribution when there are a small number of terminals to which the file or the bundle of files is to be delivered.  
         [0013]     The File Distribution Function can use the functions defined in another OMA BCAST, and can encrypt the file or file bundle by the schemes provided in the Content Protection or Service Protection Function. The File Distribution Function can be provided with a broadcast-based error resilience function such as Forward Error Correction (FEC), and can also be provided with a post-delivery scheme such as file repair over iterative session.  
         [0014]      FIG. 2  is a diagram illustrating a File Distribution Architecture defined in the OMA BCAST.  
         [0015]     Referring to  FIG. 2 , blocks related to file distribution include functional entities of a File Application Function (FA)  202 , a File Delivery Function (FD)  203 , and a File Deliver Client Function (FD-C)  205 .  
         [0016]     The FA  202 , included in the BSA, receives the file or file bundle broadcast from a Content Creation (CC)  201  and delivers not only the file but also file attribute and additional information to a BCAST Service Distribution/Adaptation (BSD/A). The FA  202  is not limited in the type and encoding scheme of the file delivered through an FD-1 interface  211 . If Content Protection is achieved by the BCAST, the FA  202  can cooperate with a Content Protection Function to encrypt the file. The FA  202  provides file attribute and location information such as the type and valid period of the file and additional information such as user profile and preference, for BCAST service.  
         [0017]     The FD  203  is responsible for the delivery, aggregation and adaptation of a file or bundle of files. The FD  203  receives not only the file and file bundle, but also a file with attribute from the FA  202  via an FD-2 interface  212 . File delivery may take place in one of the following modes.  
         [0018]     BDS Transparent Mode: Using configured attributes and attributes received from the FA  202 , the FD  203  negotiates the bearers to be used for file distribution in cooperation with the BDS Service Distribution (BDS-SD) through an FD-B1 interface  217 . If the BDS-SD does not exist, then an X-1 or X-2 interface can be used. The FD  203  normally delivers IP flows (containing a file or bundle of files) to terminals via an FD-5 interface  215 . If the FD  203  receives a request for retransmission or error reporting from the terminal, the FD  203  may transmit parts of a file or parts of a bundle of files over an interaction channel via FD-6  216 .  
         [0019]     BDS assisted mode: The FD  203  can also deliver IP flows (containing a file or a bundle of files) to the BDS via FD-B1  217 . Thereafter, the BDS-SD distributes a file or a bundle of files to the terminal.  
         [0020]     The FD  203  can aggregate files transmitted from different FAs according to provisioning information and adapt a file or a bundle of files for the BDS.  
         [0021]     In the BDS transparent mode, the FD  203  takes responsibility for error efficient and error resilient file delivery. Consequently, the FD  203  may employ different schemes for improving file delivery success such as repetition and forward error correction (FEC). Further, in certain scenarios, the FD  203  may support file-repair functions.  
         [0022]     In addition, the FD  203  may cooperate with the Service Protection Function to encrypt the bearer to be used for file delivery. If a file generated by the BCAST Subscription Management (BSM) needs to be transmitted over an FD-5 interface  215  or an FD-6 interface  216 , hen the FD  203  receives the corresponding file through an FD-4 interface  214 .  
         [0023]     The FD-C  205  in the terminal is responsible for receiving a file or bundle of files over a broadcast channel or an interaction channel through either an FD-5 interface  215  or an FD-6 interface  216 . If the service protection is done by the BCAST, the FD-C  205  may cooperate with the Service Protection Function to decrypt the bearer containing the file. If the content protection is done by the BCAST, the FD-C  205  may cooperate with the Content Protection Function to decrypt the file. In the BDS transparent mode, the FD-C  205  should be able to receive the FD transmission as it is coded for error resilience. The FD-C  205  forwards the information about file to a relevant function. For post error recovery, the terminal may be able to request missing parts of encoded files in order to fully reconstruct the delivered files. In addition, the FD-C  205  may send a report of fully or partially received files or file bundles if the terminal has the interaction ability.  
         [0024]     A description of the interfaces illustrated in  FIG. 2  is given in Table 3 below by way of example. In Table 3, a description of only the parts necessary in embodiments of the present invention is given, and a description of additional or unnecessary parts is omitted.  
                           TABLE 3                               Reference           No.   Interface   point   Description                   211   FD-1   BCAST-1   Delivery of a file, whose type and                   encoding scheme may be agnostic to                   BCAST Standard.       212   FD-2   BCAST-2   Delivery of a file (or files) or a                   content protected file (or files) to                   FD; and Delivery of an attribute of                   a file (or files) to FD.       214   FD-4   BCAST-4   Delivery of a message or a data to                   be transmitted over FD-5 or FD-6.                   The example of a message or a data                   can be notification or service guide.       215   FD-5   BCAST-5   Unidirectional delivery of a file or                   a bundle of files some of which may                   be content protected. Unidirectional                   delivery of a content and service                   protected file or a bundle of files.                   Unidirectional delivery of in-band                   signaling for File Distribution (e.g.                   signaling used for file reception).       216   FD-6   BCAST-6   Point-to-point delivery of file parts                   needed in order to reconstruct a                   complete file or file bundle on the                   terminal side following reception of                   file parts over the broadcast channel;                   Point-to-Point delivery of a file or                   a bundle of files; and Delivery of a                   request or a report about file re-                   pairing from Terminal.       217   FD-B1   BDS-1   Delivery of a file or a bundle of                   files to BDS; Delivery of a service                   and/or content protected file or a                   bundle of files to BDS; Delivery of                   attribute of a file or a bundle of                   files to determine bearers used for                   file distribution; and Delivery of                   bearer information used for a file                   or bundle of files distribution.                  
 
         [0025]     As described with reference to  FIG. 2 , a definition of only the functional entities for file distribution is provided, and there is no definition of (i) how to actually perform file distribution, (ii) which control messages should be transmitted between functional entities for actual file distribution, and (iii) how the functions to be provided in the File Distribution Function should be realized in detail.  
         [0026]     Accordingly, a need exists for a system and method for defining the functional entities for file distribution, and further defining how to actually perform file distribution, which control messages should be transmitted between functional entities for actual file distribution, and how the functions to be provided in the File Distribution Function should be realized.  
       SUMMARY OF THE INVENTION  
       [0027]     It is, therefore, an object of embodiments of the present invention to substantially solve the above and other problems, and provide a method for efficiently delivering at least one file in a mobile broadcast system, and a system thereof.  
         [0028]     It is another object of embodiments of the present invention to provide a method for delivering at least one file over a broadcast channel or an interaction channel according to circumstances in a mobile broadcast system, and a system thereof.  
         [0029]     It is another object of embodiments of the present invention to provide a method in which upon receiving at least one file, a terminal can send a retransmission request for the received file in a mobile broadcast system, and a system thereof.  
         [0030]     It is yet another object of embodiments of the present invention to provide a method in which upon receiving at least one file, a terminal can send a reception report for the received file in a mobile broadcast system, and a system thereof.  
         [0031]     It is still another object of embodiments of the present invention to provide a method in which an OMA BCAST delivers at least one file to the BDS and the BDS reconstructs the file in the way supported by the BDS and delivers it to a plurality of terminals in a mobile broadcast system, and a system thereof.  
         [0032]     It is still another object of embodiments of the present invention to provide a method for delivering a transmission start of at least one file to a plurality of terminals in a mobile broadcast system, and a system thereof.  
         [0033]     According to one aspect of embodiments of the present invention, a method is provided for providing a broadcast service (BCAST) in a mobile broadcast system that receives contents of broadcast services from a content creation and provides the broadcast services to at least one terminal or at least one group of terminals via one of a broadcast distribution system (BDS) and an interaction network. The method comprises the steps of receiving, by a file application function (FA) that provides a file attribute related to the broadcast service, at least one file to be provided to at least one terminal and attribute information for the file, from the content creation, and then delivering the received file and attribute information to a file delivery function (FD) in a BCAST service distribution/adaptation (BSD/A). The method further comprises generating, by the FD, at least one bundle of files using the at least one received file based on service configuration information of a file transmitted from a BCAST subscription management (BSM) that manages subscriber information of the terminal, and generating a BCAST file including the at least one file or one bundle of files, and negotiating, by the FD, with a BDS service distribution (BDS-SD) that controls the BDS and the interaction network, using configuration information for the BCAST file to set up a bearer for delivering the generated BCAST file. The method still further comprises, after completion of setting up the bearer, delivering by the FD the BCAST file to a terminal subscribed to the broadcast service.  
         [0034]     According to another aspect of embodiments of the present invention, a mobile broadcast system is provided that receives contents of broadcast services (BCAST) from a content creation and provides the broadcast services to at least one terminal or at least one group of terminals via one of a broadcast distribution system (BDS) and an interaction network. The system comprises a file application function (FA) for receiving at least one file to be provided to at least one terminal and attribute information for the file, from the content creation, performing content protection on the at least one file, and delivering the content-protected at least one file and the attribute information for the file to the terminal. The system further comprises a file delivery function (FD) for generating a BCAST file such that it can deliver the at least one received file based on service configuration information of a file transmitted from a BCAST subscription management (BSM) that manages subscriber information of the terminal, negotiating with a BDS service distribution (BDS-SD) that controls the BDS and the interaction network to set up a bearer for delivering the generated BCAST file, performing service protection on the bearer such that a terminal not subscribed to the broadcast service cannot receive the BCAST file, and then delivering the BCAST file to a terminal subscribed to the broadcast service. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0035]     The above and other objects, features and advantages of embodiments of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:  
         [0036]      FIG. 1  is a diagram illustrating a logical configuration of a mobile broadcast system proposed in the BCAST Working Group of OMA;  
         [0037]      FIG. 2  is a diagram illustrating a File Distribution Architecture defined in the OMA BCAST;  
         [0038]      FIG. 3  is a signal flow diagram illustrating an exemplary process of delivering a file over a broadcast channel in a mobile broadcast system according to a first embodiment of the present invention;  
         [0039]      FIG. 4  is a signal flow diagram illustrating an exemplary process of processing a corresponding operation using a broadcast channel when a terminal receiving OMA BCAST file service sends a retransmission request in a mobile broadcast system according to an embodiment of the present invention;  
         [0040]      FIG. 5  is a signal flow diagram illustrating an exemplary process of processing a corresponding operation using an interaction channel when a terminal receiving OMA BCAST file service sends a retransmission request in a mobile broadcast system according to an embodiment of the present invention;  
         [0041]      FIG. 6  is a signal flow diagram illustrating another exemplary process of processing a corresponding operation using an interaction channel when a terminal receiving OMA BCAST file service sends a retransmission request in a mobile broadcast system according to an embodiment of the present invention;  
         [0042]      FIGS. 7, 8  and  9  are signal flow diagrams illustrating exemplary terminal report processes in a mobile broadcast system according to an embodiment of the present invention; and  
         [0043]      FIG. 10  is a signal flow diagram illustrating an exemplary process of delivering a file over a broadcast channel in a mobile broadcast system according to a second embodiment of the present invention. 
     
    
       [0044]     Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures.  
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0045]     Exemplary embodiments of the present invention will now be described in detail with reference to the annexed drawings. In the following description, a detailed description of known functions and configurations incorporated herein has been omitted for clarity and conciseness.  
         [0046]     Embodiments of the present invention propose a message sequence chart related to efficient and stable delivery of a file or a bundle of files, a user report and error recovery in file distribution in a mobile broadcast system.  
         [0047]     In particular, embodiments of the present invention propose a method for delivering a file distribution-related message based on the OMA File Distribution Architecture as shown in  FIG. 2 .  
         [0048]     In the following description, the present invention will present a typical message sequence chart according to embodiments of the present invention. For convenience, the entities and names defined in 3GPP which is a standard organization for the asynchronous mobile communication, or OMA which is a standard organization for mobile application will be used herein, but embodiments of the present invention are not limited thereto.  
         [0049]      FIG. 3  is a signal flow diagram illustrating an exemplary process of delivering a file over a broadcast channel in a mobile broadcast system according to a first embodiment of the present invention. It is assumed for example, that CC, BSA, BSD/A, BDS-SD, and terminal perform the functions substantially as described in Table 1, and the FA, FD, and FD-C perform the functions described in the File Distribution Architecture. In addition, it should be noted in the signal flow diagram that the parts shown by a solid line represent mandatory operations, while the parts shown by a dotted line represent optional operations.  
         [0050]     Referring to  FIG. 3 , a Content Creation (CC)  301  delivers a file attribute to an FA  302  along with at least one file to provide file distribution service to a terminal in step  1 . The FA  302  performs a Content Protection Function  310  for the received file when necessary. The Content Protection Function  310  performs content protection so that the file is not restored in terminals other than an appropriate terminal. The FA  302  delivers the content-protected at least one file and file attribute to an FD  303  in step  2 . The FD  303  may perform a File Aggregation Function  311  for generating a bundle of files to provide BCAST file service for a plurality of files received from a plurality of FAs according to service configuration information such as service schedule, service type and service category. The File Aggregation Function  311  can generate a plurality of files into a plurality of file bundles and provide the file bundles for each individual package. Further, the FD  303  may provide BCAST file service not only with the file bundle but also with one file. The service configuration information, although not shown in  FIG. 3 , is provided from the BSM shown in  FIG. 1 .  
         [0051]     The FD  303  delivers configuration information such as Quality-of-Service (QoS) requested by the BCAST file service and a necessary data rate to a BDS-SD  304  in step  3 , to set up a bearer used for delivery of the BCAST file. Based on the configuration information received from the FD  303 , the BDS-SD  304  sets up the bearer to be used by the BCAST file service and then provides the bearer information to be used for file distribution to the FD  303  in response to the configuration information in step  4 .  
         [0052]     Upon receiving the bearer information, the FD  303  performs a Service Protection Function  312  to protect a bearer over which the BCAST service is to be transmitted, such that subscribers not subscribed to the BCAST file service cannot receive the BCAST file service. When necessary or when the user makes the request during its service subscription, the FD  303  can notify a start of file delivery to an FD-C  305 . In the file delivery notification method, the FD  303  can directly notify the start of file delivery to all subscribers in the service area through the BDS for the FD-C  305  in step  5 . In an alternative notification method, if the request is sent to the BDS-SD  304  in step  5 , the BDS-SD  304  assigns available or appropriate BDS and notifies the start of file delivery to the FD-C  305  in step  6   b.    
         [0053]     After the notification, the FD  303  delivers the service-protected BCAST file service to an FD-C  305  through the BDS in step  8 . The typical technology that can be used for the Service Protection Function  312  can comprise Internet Protocol (IP) Security specified in IETF.  
         [0054]      FIG. 4  is a signal flow diagram illustrating an exemplary process of processing a corresponding operation using a broadcast channel when a terminal receiving OMA BCAST file service sends a retransmission request in a mobile broadcast system according to an embodiment of the present invention.  FIG. 4  illustrates another example in which OMA BCAST file service is transmitted over a broadcast channel. The retransmission is performed when repairing is achieved because terminals have failed to receive the transmitted OMA BCAST file service, or when a particular BCAST file service is transmitted to a previously known subscriber. In  FIG. 4 , the BSD/A, BDS-SD, and terminal perform the functions substantially as described in Table 1, and the FA  403  and FD-C  405  are the entities described in the File Distribution Architecture.  
         [0055]     Referring to  FIG. 4 , the FD-C  405  sends a retransmission request for all or portion of a file to an FD  403  in step  1 . That is, in embodiments of the present invention, the terminal can receive all or portion of the retransmitted file. When sending a retransmission request for all of the files, the FD-C  405  may include in the retransmission request the file identifiers used for identifying the files or the transmission identifiers for the files used for the delivery of the files, and allow the FD  403  to determine for which file the FD-C  405  sent the retransmission request. When sending a retransmission request for some of the files, the FD-C  405  may include in the retransmission request the identifiers used for identifying some of the files to allow the FD  403  to distinguish the some of the files. The identifiers used for identifying some of the files can comprise session identifiers used for identifying the some of the files during delivery of the files, or identifiers for blocked files when the files are blocked before being delivered. The identifiers used for identifying the some of the files may also include identifiers for locations of the terminals during the retransmission request so that the FD  403  can refer to them.  
         [0056]     The FD  403  responds to the request from the FD-C  405  in step  2 . The response to the request is optional. In the description of  FIG. 4 , the FD  403  performs retransmission for all or portion of the file using a broadcast channel in response to the request of the terminal.  
         [0057]     After receiving the user&#39;s request, the FD  403  can determine whether it will use an interaction channel or a broadcast channel for the file delivery. It is assumed for example in  FIG. 4  that the FD  403  determines to use the broadcast channel.  
         [0058]     The FD  403  selects a configuration of the corresponding files and a file transmission area according to locations of the terminals in step  411 . Thereafter, the FD  403  sends a message for requesting assignment of a bearer for file delivery to a BDS-SD  404  in step  3 . In order to determine the file transmission area according to locations of the terminals, the message may include therein location information of the area where the terminal is located during the user&#39;s request in step  1 . The location information can comprise area identifiers set in BDS or area identifiers set in OMA BCAST. The BDS-SD  404  delivers information and attribute for an available bearer to the FD  403  in response to the corresponding request in step  4 . However, the BDS-SD  404  may deny the request when it has no resource for the bearer assignment.  
         [0059]     Upon receiving the information and attribute for the bearer from the BDS-SD  404 , the FD  403  performs a Service Protection Function  412  for bearer protection based on the received information. Thereafter, the FD  403  starts retransmission for the requested files through the corresponding BDS in step  5 .  
         [0060]      FIG. 5  is a signal flow diagram illustrating an exemplary process of processing a corresponding operation using an interaction channel when a terminal receiving OMA BCAST file service sends a retransmission request in a mobile broadcast system according to an embodiment of the present invention. It is assumed herein that the BSD/A, BDS-SD, interaction network, and terminal perform the functions substantially as described in Table 1, and the FD and FD-C perform the functions substantially as described in the File Distribution Architecture.  
         [0061]     Referring to  FIG. 5 , an FD-C  506  sends a message for requesting retransmission of all or portion of a file to an FD  503  using an interaction channel in step  1 . A format of the request message can be equal to that described with reference to  FIG. 4 . That is, the request message comprises at least file information and location information. Upon receiving the request message, the FD  503  sends a response to the request to the terminal in step  2 . However, the response to the request is optional. When sending no response to the request, the FD-C  506  can recognize acceptance of its own request by the FD  503 , as it is aware of the delivery start of all or portion of the file.  
         [0062]     After receiving the retransmission request, the FD  503  fully or partially configures the corresponding file in step  511 . Thereafter, the FD  503  sends an assignment request for a bearer for file delivery to a BDS-SD  504  in step  3 . The BDS-SD  504  sends an assignment request for the bearer used for file delivery to an interaction network  505  in step  4 . The interaction network  505  determines a bearer based on the request and delivers the determined bearer information to the BDS-SD  504  in step  5 . Thereafter, the BDS-SD  504  finally delivers information and attribute for an available bearer to the FD  503  in step  6 . The FD  503  can perform a Service Protection Function  512  for bearer protection based on the corresponding information.  
         [0063]     Thereafter, the BDS-SD  504  can send a notification message indicating the start of file delivery to the FD-C  506 . In this case, the FD  503  first sends a notification message indicating the start of the file delivery to the BDS-SD  504  in step  7 . There are two possible methods for sending the notification message to the FD-C  506 . In a first method, upon receiving the notification message, the BDS-SD  504  forwards the notification message to the interaction network  505  in step  7   a,  and the interaction network  505  forwards the notification message to the FD-C  506  in step  7   b.  In a second method, upon receiving the notification message, the BDS-SD  504  directly forwards the notification message to the FD-C  506  in step  7 c. The interaction network  505  sends a response message to the BDS-SD  504  in response to the notification message in step  8 . Upon receiving the response message, the BDS-SD  504  forwards the response message to the FD  503  in step  9 . Thereafter, the FD  503  delivers a retransmission file to the FD-C  506  over an interaction channel.  
         [0064]     There are two possible methods for delivering the retransmission file. In a first method, the FD  503  delivers the retransmission file to the interaction network  505  in step  10 , and then the interaction network  505  performs a Service Protection Function  513  on the retransmission file and delivers the resultant retransmission file to the FD-C  506  over an interaction channel in step  11 . In a second method, the FD  503  directly delivers the retransmission file to the FD-C  506  in step  12 .  
         [0065]      FIG. 6  is a signal flow diagram illustrating another exemplary process of processing a corresponding operation using an interaction channel when a terminal receiving OMA BCAST file service sends a retransmission request in a mobile broadcast system according to an embodiment of the present invention. It is assumed for example herein that the BSD/A, interaction network, and terminal perform the functions substantially as described in Table 1, and the FD and FD-C perform the functions substantially as described in the File Distribution Architecture.  
         [0066]     Referring to  FIG. 6 , an FD-C  606  sends a message for requesting retransmission of all or portion of a file to an FD  603  in step  1 . Upon receiving the request message, the FD  603  sends a response message to the FD-C  606  in response to the request message in step  2 . Sending the response message to the FD-C  606  is optional according to the system. Upon receiving the retransmission request, the FD  603  configures a corresponding file in step  611 . Thereafter, the FD  603  sends a request for assignment of a bearer to be used for file delivery to an interaction network  605  in step  3 . The interaction network  605  detects an available bearer and delivers information on an assigned bearer to the FD  603  in step  4 . Upon receiving the bearer information, the FD  603  performs a Service Protection Function  612  for bearer protection based on the bearer information.  
         [0067]     After performing the Service Protection Function  612 , the FD  603  can send a notification message indicating the start of file delivery to the FD-C  606 . The FD  603  sends the notification message to the FD-C  606  via the interaction network  605  in steps  5  and  6 . The interaction network  605  sends a response message to the FD  603  in response to the notification message in step  7 .  
         [0068]     There are two possible methods for delivering the service-protected file after sending the notification message. In a first method, the FD  603  delivers a retransmission file to the interaction network  605  in step  8 . Thereafter, the interaction network  605  performs a Service Protection Function  613  on the retransmission file for an interaction channel, and delivers the corresponding retransmission file to the FD-C  606  in step  9 . In a second method, the FD  603  directly delivers the service-protected retransmission file to the FD-C  606  in step  10 .  
         [0069]      FIG. 7  is a signal flow diagram illustrating an exemplary terminal report process in a mobile broadcast system, wherein the terminal report is received at an FD in a BSD/A, according to an embodiment of the present invention. It is assumed for example herein that the BSD/A, BDS-SD, interaction network, and terminal perform the functions substantially as described in Table 1, and the FD and FD-C perform the functions substantially as described in the File Distribution Architecture.  
         [0070]     Referring to  FIG. 7 , an FD-C  706  sends a report for reception of OMA BCAST file service to an FD  703  in a BSD/A via an interaction network  705  in step  1 . Upon receiving the report, the FD  703  sends a response indicating the receipt of the report to the FD-C  706  in step  2 . The response to the report is optional according to the system. The contents of the report can comprise various information such as the quality of the OMA BCAST file service. The quality can comprise data regarding an IP packet error rate or a file block error.  
         [0071]     Upon receiving the report, the FD  703  analyzes the received report in step  711 . Thereafter, the FD  703  delivers the analysis result of the report to a BDS-SD  704  in step  3 . Based on the analysis result of the report, the BDS-SD  704  determines whether an error correction scheme used for delivering the OMA BCAST file service in the BDS is appropriate and whether transmission power assigned for the file service is appropriate, and if inappropriate, can change the transmission power for the file service during retransmission and/or for use even during delivery of another file service.  
         [0072]     Upon receiving the report, the BDS-SD  704  sends a response message in response to the report in step  4 . Sending the response to the report is optional according to the system.  
         [0073]      FIG. 8  is a signal flow diagram illustrating another exemplary terminal report process in a mobile broadcast system, wherein the terminal report is received at a BDS-SD  804 , according to an embodiment of the present invention. It is assumed for example herein that the BSD/A, BDS-SD, interaction network, and terminal perform the functions substantially as described in Table 1, and the FD and FD-C perform the functions substantially as described in the File Distribution Architecture.  
         [0074]     Referring to  FIG. 8 , an FD-C  805  sends a report for the file reception to a BDS-SD  804  via an interaction network  806  in step  1 . Thereafter, the BDS-SD  804  may send a response indicating the receipt of the report to the FD-C  805  in step  2 . Sending the response indicating the receipt of the report is optional according to the system. The contents of the report can comprise various information such as the quality of the OMA BCAST file service. The quality can comprise data regarding an IP packet error rate or a file block error.  
         [0075]     Upon receiving the report, the BDS-SD  804  analyzes the received report in step  811 , and then can deliver the reception report to an FD  803  in a BSD/A in step  3 .  
         [0076]     Based on the received report, the FD  803  determines whether a forward error correction scheme applied to the OMA BCAST file service is appropriate, and if inappropriate, can determine to use an error correction scheme with a higher performance.  
         [0077]     Upon receiving the report, the FD  803  sends a response message to the report in step  4 . Sending the response message to the report is optional according to the system.  
         [0078]      FIG. 9  is a signal flow diagram illustrating another exemplary terminal report process in a mobile broadcast system, wherein the terminal report is received at an interaction network, according to an embodiment of the present invention. It is assumed for example herein that the BSD/A, BDS, interaction network and terminal perform the functions substantially as described in Table 1, and the FD and FD-C perform the functions substantially as described in the File Distribution Architecture.  
         [0079]     Referring to  FIG. 9 , an FD-C  905  sends a report for the file reception to an interaction network  906  in step  1 . Thereafter, the interaction network  906  sends a response indicating the receipt of the report for the file reception to the FD-C  905  in step  2 . Sending the response to the report is optional according to the system. Upon receiving the report, the interaction network  906  forwards the received report to an FD  903  in step  3 . Upon receiving the report, the FD  903  sends a response message to the received report in step  4 .  
         [0080]      FIG. 10  is a signal flow diagram illustrating an exemplary process of delivering a file over a broadcast channel in a mobile broadcast system according to a second embodiment of the present invention, wherein an FD delivers OMA BCAST file service via a BDS instead of directly delivering the OMA BCAST file service. It is assumed for example that the CC, BSA, BSD/A, BDS-SD, and terminal perform the functions substantially as described in Table 1, and the FA, FD and FD-C perform the functions substantially as described in the File Distribution Architecture.  
         [0081]     Referring to  FIG. 10 , a Content Creation (CC)  1001  delivers a file attribute to an FA  1002  along with at least one file to provide file distribution service to a terminal in step  1 . The FA  1002  performs a Content Protection Function  1011  for the received file. The Content Protection Function has been described in detail with reference to  FIG. 3 , so a detailed description thereof will be omitted here. The FA  1002  delivers the content-protected at least one file and an attribute value for setting up a bearer for delivery of the file, to an FD  1003  in step  2 .  
         [0082]     The FD  1003  performs a file aggregation function for generating a bundle of files to provide BCAST file service for a plurality of files received from a plurality of FAs according to service configuration information in step  1012 . As described with reference to  FIG. 3 , the FD  1003  can provide BCAST file service in the form of one file or a bundle of files. The service configuration information is received from a BSM. The FD  1003  can notify of the start of the delivery of the BCAST file to a BDS-SD  1004  when necessary. In this case, before the file delivery, the FD  1003  notifies the file delivery to the BDS-SD  1004  in step  3 . Then the BDS-SD  1004  sends a response message to the notification to the FD  1003  in step  4 . Sending the response message to the notification is optional according to the system.  
         [0083]     Upon receiving the response to the notification, the FD  1003  delivers an intended BCAST file to the BDS-SD  1004  in step  5 . Upon receiving the BCAST file, the BDS-SD  1004  performs a service protection function and a BDS-specific task in step  1013 . For example, the BDS-specific task comprises a task for changing its format to be suitable for the BDS. Thereafter, the BDS-SD  1004  notifies of the start of file delivery in step  6 , and delivers the file to an FD-C  1005  in step  7 .  
         [0084]     As can be understood from the foregoing description, the file distribution method according to embodiments of the present invention defines a message sequence chart, thereby enabling accurate file delivery. In addition, embodiments of the present invention provide a specific retransmission and report method for the case where a terminal fails to normally receive a file due to an error, thereby making it possible to efficiently process the file.  
         [0085]     While the invention has been shown and described with reference to certain exemplary 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.