Abstract:
A method and system are provided for delivering a stream in a mobile broadcast system that receives stream contents of broadcast services (BCAST) from a content creation and provides the broadcast services to one terminal or one group of terminals via one of a broadcast distribution system (BDS) and an interaction network. The method involves requesting assignment of a bearer in which the stream is to be delivered, assigning a bearer in response to the bearer assignment request, adapting the stream to be appropriate for the assigned bearer, and delivering the adapted stream to the terminal in the assigned bearer.

Description:
PRIORITY 
     This application claims the benefit under 35 U.S.C. §119(a) of a Korean Patent Application filed in the Korean Intellectual Property Office on Apr. 2, 2005 and assigned Serial No. 2005-27834, the entire disclosure of which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a stream delivery apparatus and method for receiving broadcasts in a mobile broadcast system. More particularly, the present invention relates to a stream delivery apparatus and method for efficiently receiving streams at a mobile terminal in a mobile broadcast system. 
     2. Description of the Related Art 
     The mobile communication market continues to create new services through recombination or integration of the existing technologies. With the recent development of the communication and broadcast technologies, the broadcast system or the mobile communication system is now in the phase of providing broadcast service using mobile terminals such as cellular phone and Personal Digital Assistance (PDA). Live discussions are made not only on the common broadcast service limited to the voice and image, but also on Mobile Broadcast Service (BCAST) capable of transmitting packet data over a broadcast channel. 
     Mobile Broadcast Service can include processes of discovering a service by a mobile terminal capable of receiving Mobile Broadcast Service, subscribing to the service by the mobile terminal, providing various control information for receiving the service, transmitting the service, and receiving the service by the mobile terminal. 
       FIG. 1  is a diagram illustrating a logical architecture for a mobile broadcast system proposed by BCAST working group of Open Mobile Alliance (OMA) that has established the technical standard for Application Layer and its lower Transport Layer and Network Layer for Mobile Broadcast Service. That is,  FIG. 1  illustrates the BCAST network architecture supporting Mobile Broadcast Service. Herein,  FIG. 1  illustrates the architecture for OMA BCAST Service, which is an OMA Mobile Broadcast Service standard. 
     In OMA BCAST, the technical fields and functions being discussed for Mobile Broadcast Service include a service guide having information on Mobile Broadcast Service, necessarily required 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 capable of indicating a start of Mobile Broadcast Service and a change in Mobile Broadcast Service. These functions are located in BCAST logical entities shown in  FIG. 1 . A description will now be made of the logical entities constituting the mobile broadcast system shown in  FIG. 1 . The logical entities shown in  FIG. 1  are shown in Table 1, and interfaces between the entities are shown in Table 2. 
     
       
         
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 No. 
                 Entity name 
                 Functionality 
               
               
                   
               
             
             
               
                 102 
                 BCAST Service 
                 Represents the service application of the BCAST Service, such as 
               
               
                   
                 Application (BSA) 
                 streaming 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 delivery of BCAST Services, and 
               
               
                   
                 Distribution/Adaptation 
                 performs the adaptation of the BCAST Enabler to underlying 
               
               
                   
                 (BSD/A) 
                 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 Subscription 
                 Responsible for service provisioning such as subscription and 
               
               
                   
                 Management (BSM) 
                 payment related functions, the provision of information used for 
               
               
                   
                   
                 BCAST Service reception, and BCAST Terminal management. 
               
               
                   
                   
                 It provides the functionality of Notification, 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, content protection 
               
               
                   
                   
                 information. The user device may support the interactive channel in 
               
               
                   
                   
                 which case it would be able to directly communicate to the network 
               
               
                   
                   
                 regarding the available services. 
               
               
                 101 
                 Content Creation (CC) 
                 Source of content, may provide support for delivery paradigms (e.g. 
               
               
                   
                   
                 streaming servers); provides base material for content descriptions. 
               
               
                 111 
                 BDS Service 
                 Responsible for the coordination and delivery of broadcast services to 
               
               
                   
                 Distribution 
                 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 Distribution 
                 Specific support for the distribution of content over the broadcast 
               
               
                   
                 System (BDS) 
                 channel. This may involve the same or different radio network from 
               
               
                   
                   
                 that used by the interactive channel. 
               
               
                 113 
                 Interaction Network 
                 Specific support for the interaction channel. This may involve the 
               
               
                   
                   
                 same or different radio network from that used by the broadcast 
               
               
                   
                   
                 channel. 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 No. 
                 Reference point name 
                 Usage 
               
               
                   
               
             
             
               
                 121 
                 BCAST-1 
                 Content, Content attributes, notification event, etc. 
               
               
                 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 attributes, User preference and 
               
               
                   
                   
                 subscription information. User request, User reporting, notification 
               
               
                   
                   
                 event and maybe user charging information 
               
               
                 124 
                 BCASTA-4 
                 Notification, Service Guide, fragments (related to provisioning, 
               
               
                   
                   
                 purchasing, subscription, terminal provisioning, etc.), Service keys, 
               
               
                   
                   
                 Terminal Provisioning object, Terminal Provisioning message, 
               
               
                   
                   
                 Terminal management message, etc. 
               
               
                 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 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 
                 BDS-1 
                 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 
                 BDS-2 
                 Service provisioning, Subscription information, Device management, 
               
               
                   
                   
                 Security material. 
               
               
                 131 
                 X-1 
                 Reference Point between BDS Service Distribution and BDS 
               
               
                 132 
                 X-2 
                 Reference Point between BDS Service Distribution and Interaction 
               
               
                   
                   
                 Network 
               
               
                 133 
                 X-3 
                 Reference Point between BDS and Terminal 
               
               
                 134 
                 X-4 
                 Reference Point between BDS Service Distribution and Terminal over 
               
               
                   
                   
                 Broadcast 
               
               
                 135 
                 X-5 
                 Reference Point between BDS Service Distribution and Terminal over 
               
               
                   
                   
                 Interaction Channel 
               
               
                 136 
                 X-6 
                 Reference Point between Interaction Network and Terminal 
               
               
                   
               
             
          
         
       
     
     In the description 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. 
       FIG. 2  is an exemplary Stream Distribution Function architecture for improving BCAST Streaming Service in OMA BCAST, which is an OMA Mobile Broadcast standard organization. 
     The Stream Distribution Function converts voice and image data into streams having BCAST standard CODEC or Broadcast Distribution System (BDS) standard CODEC and distributes the converted streams to terminals. The Stream Distribution Function mainly distributes the streams over a broadcast channel, but can also transmit the streams to terminals over an interaction channel when the number of the terminals is smaller. 
     In addition, the Stream Distribution Function may use service protection capability provided by a Service Protection Function to prevent a terminal or user unauthorized to receive a streaming service from receiving the streaming service, thereby protecting data streams. The Stream Distribution Function may provide an error resilience function in which the terminal can correct a possible stream data error occurring in a wireless environment, using a Forward Error Correction (FEC) technique. 
     A description of the logical entities and interfaces shown in  FIG. 2  is given in Table 3. OMA BCAST configures three sub-functional entities to implement the Stream Distribution Function. 
     The sub-functional entities include a Stream Application Function, Stream Delivery Function, and Stream Delivery Client Function. 
     A Content Creation (CC)  101  provides voice or image data to be transmitted as BCAST Streaming Service, and the voice or image data can optionally be a stream that is encoded using BCAST standard media type and CODEC. Further, the CC  101  provides an attribute for the data so that a Stream Application Function (SA)  202  and a Stream Delivery Function (SD)  203  can perform necessary operations, and the attribute may be used for generating a service guide used for an OMA BCAST service guide. 
     The SA  202  provides a streaming service having BCAST standard media type and CODEC to a plurality of users or user terminals. The SA  202  receives transmission data for the streaming service from the CS  101 . The data may have the CODEC and media type defined in OMA BCAST. Otherwise, the data undergoes a translation operation in the SA  202 . After completion of the translation operation, the SA  202  delivers the BCAST-standardized stream to the SD  203 , along with an attribute for the standardized stream. An exemplary attribute of the standardized stream may include a media type of the stream, a CODEC used, a data-related attribute such as a required rate, a preferred age group for the streaming service, a service area, and the like. 
     The SD  203  receives the BCAST-standardized stream from the SA  202 , and delivers the stream to a plurality of users or user terminals. Accordingly, the SD  203 , together with a BDS  112 , performs a process of determining a bearer capable of delivering the standardized stream. Further, the SD  203  performs an operation of translating the stream into a streaming service appropriate for the BDS  112 , upon receiving a request from the BDS  112 . There are two possible methods for delivering streams by the SD  203 :
         BDS transparent mode: An OMA BCAST-standardized stream is directly delivered in OMA BCAST. In this instance, the BDS  112  provides the bearers and wire/wireless resources to be used for actual transmission, and performs no other function. The SD  203  negotiates bearers to be used for stream delivery in cooperation with a BDS Service Distribution  111  through an SD-B1 interface  217  to deliver the OMA BCAST-standardized stream. If the BDS Service Distribution  111  does not exist, an X-1 interface  131  or an X-2 interface  132  can be used instead of the SD-B1 interface  217 . If the bearers are determined, the SD  203  delivers the OMA BCAST-standardized stream to a plurality of terminals via an SD-5 interface  215 .   BDS assisted mode: The SD  203  provides the OMA BCAST-standardized stream or stream data to the BDS  112 , and the BDS  112  delivers the stream to a plurality of users or user terminals through a translation process appropriate for the BDS characteristics. For the stream delivery, the SD-B1 interface  217  is used. Upon receiving the stream via the SD-B1 interface  217 , the BDS Service Distribution  111  distributes the stream to a plurality of users or user terminals after an appropriate translation process.       

     In addition, the SD  203  can translate the OMA BCAST stream into a BDS-specific stream in response to a BDS request, and also change a reproduction rate of the stream data according to the network condition of the BDS  112 . Further, the SD  203  has a function of protecting a streaming service by using a Service Protection Function to prevent a user or user terminal unauthorized to receive the streaming service from receiving the streaming service, and also a function of delivering signaling information used for reception of the streaming service. In addition, the SD  203  can provide various types of Forward Error Correction (FEC) techniques capable of reducing a delivery error rate of the streaming service taking the wireless channel environment into account. 
     A Stream Delivery Client Function (SD-C)  204  receives streams on a broadcast channel or an interaction channel via an SD-5 interface  215 , or an interface provided in the BDS  112 , has a function of decoding the service-protected streams and an error resilience function for FEC-applied streams, and can also have a function (for example, media synchronization function) necessary for reception of the streaming service. In addition, the SD-C  204  can have a function capable of reporting a reception error rate for the received streaming service according to capability of the mobile terminal. Herein, the term “capability of the terminal” refers to the capability of communicating with the SD  203  or the BDS  112  using a cellular network or other networks. 
     
       
         
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                 No. 
                 Interface 
                 Reference point 
                 Description 
               
               
                   
               
             
             
               
                 211 
                 SD-1 
                 BCAST-1 
                 Delivery of an unprocessed stream for BCAST streaming Service 
               
               
                   
                   
                   
                 Delivery of stream with media type and CODEC supported by 
               
               
                   
                   
                   
                 BCAST 
               
               
                 212 
                 SD-2 
                 BCAST-2 
                 Delivery of a stream having BCAST standard media type and 
               
               
                   
                   
                   
                 CODEC 
               
               
                   
                   
                   
                 Delivery of stream attributes to Stream Distribution Function in 
               
               
                   
                   
                   
                 BCAST Service Distribution/Adaptation 
               
               
                 215 
                 SD-5 
                 BCAST-5 
                 Unidirectional delivery of a BCAST-standardized stream. 
               
               
                   
                   
                   
                 Unidirectional delivery of a stream, which is adapted to BDS 
               
               
                   
                   
                   
                 specific condition(.e.g a data rate supported by BDS) 
               
               
                   
                   
                   
                 Unidirectional delivery of in-band signaling for Stream 
               
               
                   
                   
                   
                 Distribution(e.g. signaling used for stream reception) 
               
               
                 216 
                 SD-6 
                 BCAST-6 
                 Delivery of report about a stream reception 
               
               
                   
                   
                   
                 Delivery of request from terminal e.g. request for the retransmission 
               
               
                   
                   
                   
                 of a whole stream 
               
               
                 217 
                 SD-B1 
                 BCAST-1 
                 Delivery of a stream to BDS 
               
               
                   
                   
                   
                 Delivery of a protected stream to BDS 
               
               
                   
                   
                   
                 Delivery of a stream attribute to determine bearers used for stream 
               
               
                   
                   
                   
                 distribution 
               
               
                   
                   
                   
                 Delivery of bearer information used for a stream distribution 
               
               
                   
                   
                   
                 Delivery of a BDS specific profiles for the adaptation of Stream to 
               
               
                   
                   
                   
                 BDS 
               
               
                   
               
               
                 Note: 
               
               
                 If BDS service distribution does not exist, then x-1 and/or x-2 can be used for the same purpose 
               
             
          
         
       
     
     As described with reference to  FIG. 2 , the functional entities for stream distribution are defined. However, definitions of (i) how to actually perform stream distribution, (ii) which control messages should be delivered between the functional entities for actual stream distribution, and (iii) how the functions to be provided in the Stream Distribution Function should be implemented. 
     SUMMARY OF THE INVENTION 
     An aspect of exemplary embodiments of the present invention is to address at least the above problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of exemplary embodiments of the present invention is to provide an apparatus and method for efficiently delivering streams in a mobile broadcast system. 
     It is another object of an exemplary embodiment of the present invention to provide an apparatus and method in which upon receiving a stream, a user or user terminal reports the receipt of the stream in a mobile broadcast system. 
     It is further an object of an exemplary embodiment of the present invention to provide an apparatus and method for appropriately translating a BCAST stream into a BDS-specific stream in response to a request of a BDS in a mobile broadcast system. 
     It is yet another object of an exemplary embodiment of the present invention to provide an apparatus and method for delivering a stream to a BDS and allowing the BDS to reconstruct the stream into a BDS-specific stream and deliver the BDS-specific stream to a plurality of users or user terminals in a mobile broadcast system. 
     It is still another object of an exemplary embodiment of the present invention to provide an apparatus and method for notifying the start of stream delivery to a plurality of user or user terminals in a mobile broadcast system. 
     According to one aspect of exemplary embodiments the present invention, there is provided a method for delivering a stream in a mobile broadcast system that receives stream contents of broadcast services (BCAST) from a content creation and provides the broadcast services to at least one terminal via at least one of a broadcast distribution system (BDS) and an interaction network. The method comprises delivering, by a stream application function (SA), a stream comprising an attribute from content creation to a stream delivery function (SD); sending, by the stream delivery function, a request for bearer assignment to a BDS service distribution in order to deliver the stream; assigning, by the BDS service distribution, bearers used for stream delivery and sending a response comprising information on the assigned bearers to the stream delivery function; and delivering, by the stream delivery function, a BCAST streaming service to a stream delivery client function in the terminal over a broadcast channel. 
     According to another aspect of exemplary embodiments the present invention, there is provided a method for delivering a stream in a mobile broadcast system that receives stream contents of broadcast services (BCAST) from a content creation and provides the broadcast services to at least one terminal via at least one of a broadcast distribution system (BDS) and an interaction network. The method comprises delivering, by a stream application function (SA), a stream comprising an attribute from the content creation to a stream delivery function (SD); delivering, by the stream delivery function (SD), the stream to a BDS service distribution; and delivering, by the BDS service distribution, the stream to a stream delivery client function in the terminal. 
     According to yet another aspect of the present invention, there is provided a method for sending a report on stream reception at a terminal in a mobile broadcast system that receives stream contents of broadcast services (BCAST) from a content creation and provides the broadcast services to at least one terminal via at least one of a broadcast distribution system (BDS) and an interaction network. The method comprises receiving, by a stream delivery function, a report on stream reception, comprising reception quality, from a stream delivery client function in the terminal via the interaction network; analyzing, by the stream delivery function, the report on the stream reception; and sending, by the stream delivery function, a report on stream reception to a BDS service distribution to improve stream reception quality. 
     According to yet another aspect of exemplary embodiments the present invention, there is provided a method for sending a report on stream reception at a terminal in a mobile broadcast system that receives stream contents of broadcast services (BCAST) from a content creation and provides the broadcast services to at least one terminal via at least one of a broadcast distribution system (BDS) and an interaction network. The method comprises receiving, by a BDS service distribution, a report on stream reception, comprising reception quality, from a stream delivery client function in the terminal via the interaction network; analyzing, by the BDS service distribution, the report on the stream reception; and sending, by the BDS service distribution, a report on stream reception to a stream delivery function to improve stream reception quality. 
     According to still another aspect of exemplary embodiments the present invention, there is provided a system for delivering a stream in a mobile broadcast system that receives stream contents of broadcast services (BCAST) from a content creation and provides the broadcast services to at least one terminal or one group of terminals via at least one of a broadcast distribution system (BDS) and an interaction network. The system comprises a stream application function for, delivering a stream to a stream delivery function; the stream delivery function for sending a request for bearer assignment to a BDS service distribution in order to deliver the stream, and delivering the stream to a stream delivery client function in the terminals; and the BDS service distribution for assigning bearers used for stream delivery and sending a response with information on the assigned bearers to the stream delivery function. 
     According to still another aspect of exemplary embodiments the present invention, there is provided a system for delivering a stream in a mobile broadcast system that receives stream contents of broadcast services (BCAST) from a content creation and provides the broadcast services to at least one terminal via at least one of a broadcast distribution system (BDS) and an interaction network. The system comprises a stream application function for, delivering a the translated stream to a stream delivery function; the stream delivery function for delivering the stream to a BDS service distribution; and the bds service distribution for delivering the stream to a stream delivery client function in the terminal. 
     Other objects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of certain exemplary embodiments of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a diagram illustrating a logical architecture of OMA BCAST; 
         FIG. 2  is a diagram illustrating architecture for a Stream Distribution Function of OMA BCAST; 
         FIG. 3  is a message flow diagram in which OMA BCAST directly delivers a stream over a broadcast channel according to an exemplary embodiment of the present invention; 
         FIG. 4  is a message flow diagram in which OMA BCAST delivers OMA BCAST Streaming Service via a BDS Service Distribution instead of directly delivering the OMA BCAST Streaming Service according to an exemplary embodiment of the present invention; 
         FIG. 5  is a message flow diagram in which when OMA BCAST directly delivers a stream over a broadcast channel, a terminal sends a User Report on stream reception to a BSD/A according to an exemplary embodiment of the present invention; and 
         FIG. 6  is a message flow diagram in which a terminal sends a User Report on stream reception to a BDS Service Distribution according to an exemplary embodiment of the present invention. 
     
    
    
     Throughout the drawings, the same drawing reference numerals will be understood to refer to the same elements, features, and structures. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The matters defined in the description such as a detailed construction and elements are provided to assist in a comprehensive understanding of the embodiments of the invention. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness. 
     The present invention proposes a method for stably delivering a stream in stream distribution and delivering a User Report-related message upon receipt of the stream. 
     The present invention proposes a method for delivering a Stream Distribution-related message based on the OMA Stream Distribution Architecture shown in  FIG. 2 . 
     For convenience, the entities and names defined in OMA which is a standard organization for mobile application will be used herein, but the present invention is not limited thereto. 
       FIG. 3  is a message flow diagram in which OMA BCAST directly delivers a stream over a broadcast channel according to an exemplary embodiment of the present invention. A CS  101 , BSA  102 , BSD/A  103 , BDS Service Distribution  111 , and terminal  105  are assumed to perform the functions described in Table 1, and an SA  202 , an SD  203 , and an SD-C  204  perform the same functions as those in the Stream Distribution Architecture described in  FIG. 2 . 
     The CS  101  delivers a stream, such as a media type and CODEC information to the SA  202  along with an attribute of the stream in step  301 , to provide Stream Delivery Service to users. The SA  202  translates the received stream in step  303 , if the received stream is different from a BCAST standard stream, and delivers the stream including BCAST standard media type and CODEC to the SD  203  in step  305 . Further, the SA  202  delivers an attribute of the stream to the SD  203  to allow the SD  203  to negotiate bearers used for stream delivery with the BDS Service Distribution  111 . The SD  203  delivers a Bearer Assignment Request message for stream delivery to the BDS Service Distribution  111  via an SD-B1  217  in step  307 . The Bearer Assignment Request message includes information on Quality-of-Service (QoS) required by BCAST Streaming Service and a required data rate. Based on the request from the SD  203 , the BDS Service Distribution  111  assigns bearers to be used by the BCAST Streaming Service and provides the bearer assignment information to the SD  203  in step  309 . Further, in the case where the requirements of the BCAST are inappropriate for or incompatible with a BDS or translation is needed due to network circumstances of the BDS, the BDS Service Distribution  111  delivers the requirements to the SD  203 , if a required data rate for stream delivery is too high or several BDS-specific media types or CODECs are used for the stream. Upon receiving the bearer information to be used for stream delivery and the requirements from the BDS, the SD  203  performs Stream Adaptation in step  311  to generate a stream meeting the requirements of the BDS. In step  313 , the SD  203  performs, when necessary, Service Protection for protecting (encrypting) the bearers used for delivering the BCAST Streaming Service so that the subscribers not subscribed to the BCAST Streaming Service cannot receive the BCAST Streaming Service. The SD  203  notifies the start of stream delivery to the BDS Service Distribution  111  in step  315 . When necessary or when the user makes the request during its service subscription, the SD  203  may notify the start of stream delivery to the SD-C  204  in step  317 . In the stream delivery notification method, the SD  203  directly notifies distribution of the stream to all subscribers in the service area of the SD-C  204  via the BDS Service Distribution  111  as done in step  317 . Alternatively, after step  315 , the BDS Service Distribution  111  notifies the start of stream delivery to the SD-C  204  in step  319 . In step  317 , the SD  203  uses an SD-6 interface  216  in notifying the start of stream delivery to the SD-C  204 . If step  315  exits, the BDS Service Distribution  111  sends a response notifying the start of stream delivery to the SD  203  in step  321 . After the notification, the SD  203  delivers the service-protected BCAST Streaming Service to the SD-C  204  in the terminal  105  over a broadcast channel via the BDS  112  in step  323 . The typical technology available for the Service Protection in step  313  may include Internet Protocol Security (IP SEC) specified in IETF. 
       FIG. 4  is a message flow diagram in which OMA BCAST delivers OMA BCAST Streaming Service via a BDS Service Distribution instead of directly delivering the OMA BCAST Streaming Service according to an exemplary embodiment of the present invention. A CS  101 , BSA  102 , BSD/A  212 , BDS Service Distribution  111 , and terminal  105  are assumed to perform the functions described in Table 1, and an SA  202 , SD  203 , and SD-C  204  perform the functions described in the Stream Distribution Architecture. 
     To provide Stream Delivery Service to users, the CS  101  delivers a stream such as a media type and CODEC information to the SA  202  along with an attribute for the stream in step  401 . Thereafter, if the received stream is different from an OMA BCAST stream in terms of the media type and CODEC, the SA  202  translates the received stream into a BCAST standard stream in step  403 , and delivers the BCAST standard stream to the SD  203  in step  405 . The SD  203  adapts the OMA BCAST stream to a BDS-specific stream in step  407 , and notifies stream delivery to the BDS Service Distribution  111  in step  409 . In step  407 , the CODEC and media type used for the BDS-specific stream are assumed to have underwent pre-negotiation. Upon receiving the stream delivery notification in step  409 , the BDS Service Distribution  111  sends a response with information on the bearers to be used for stream delivery to the SD  203  in step  411 . Upon receiving the response with bearer information to be used for stream delivery from the BDS Service Distribution  111 , the SD  203  delivers the stream to the BDS Service Distribution  111  in step  413 . The BDS Service Distribution  111  performs Stream Adaptation in step  415  to determine a data rate of the stream suitable for the corresponding bearer, and when necessary, performs Service Protection for protecting (encrypting) the bearer used for delivering the BCAST Streaming Service in step  417  so that subscribers not subscribed to the BCAST Streaming Service cannot receive the BCAST Streaming Service. Thereafter, the BDS Service Distribution  111  notifies the start of stream delivery to the SD-C  204  in the terminal  105  in step  419 , and then delivers the corresponding stream via reference points X (defined in Third Generation Partnership Project (3GPP) or 3GPP2) in step  421 . 
       FIG. 5  is a message flow diagram in which when OMA BCAST directly delivers a stream over a broadcast channel, a terminal sends a User Report on stream reception to a BSD/A according to an exemplary embodiment of the present invention. A BSD/A  103 , BDS Service Distribution  111 , Interaction Network  113 , and terminal  105  are assumed to perform the functions described in Table 1, and an SD  203  and SD-C  204  perform the functions described in the Stream Distribution Architecture. 
     The SD-C  204  in the terminal  105  sends a report on stream reception to the SD  203  in the BSD/A  103  via the interaction network  113  in step  501 . Then the SD  203  may optionally send a response to the report to the SD-C  204  in step  503 . The contents of the report may include the reception quality for OMA BCAST Streaming Service. The quality may include an IP packet error rate or a stream block error rate. The SD  203  analyzes the received report in step  505 , and may send a report on stream reception to the BDS Service Distribution  111  in step  507  to improve the stream reception quality. After the analysis process, the SD  203  may perform an operation of changing an FEC scheme to improve the stream quality. Based on the report, the BDS Service Distribution  111  determines whether the FEC scheme used in the BDS  112  for delivering the OMA BCAST Streaming Service is appropriate or compatible and whether transmission power allocated for the streaming service is appropriate. If inappropriate, the BDS Service Distribution  111  may use the report during delivery of other streaming services. 
     The BDS Service Distribution  111  may send a response to the report on stream reception to the SD  203  in step  509 . 
       FIG. 6  is a message flow diagram in which a terminal sends a User Report on stream reception to a BDS Service Distribution according to an exemplary embodiment of the present invention. A BSD/A  103 , BDS Service Distribution  111 , Interaction Network  113 , and terminal  105  are assumed to perform the functions described in Table 1, and an SD  203  and SD-C  204  perform the functions described in the Stream Distribution Architecture. 
     The SD-C  204  in the terminal  105  may send a report on stream reception to the BDS Service Distribution  111  via the interaction network  113  in step  601 , and the BDS Service Distribution  111  may send a response to the report to the SD-C  204  in step  603 . The contents of the report may include the reception quality for OMA BCAST Streaming Service. The quality may include an IP packet error rate or a stream block error rate. The BDS Service Distribution  111  may analyze the received report in step  605 , and then may send a report on stream reception to the SD  203  in the BSD/A  103  in step  607 . 
     Based on the received report, the SD  203  determines whether the FEC scheme used for delivering the OMA BCAST Streaming Service is appropriate. If inappropriate, the SD  203  may use the report to change the FEC scheme during delivery of other streaming services. 
     The SD  203  may send a response to the report on stream reception to the BDS Service Distribution  111  in step  609 . 
     As a result, the present invention may efficiently deliver streams in a mobile broadcast system. 
     Further, according to the exemplary embodiments of the present invention, a user or user terminal receiving a stream may send a report on reception quality of the stream. 
     In addition, the mobile broadcast system according to exemplary embodiments of the present invention delivers a stream to a BDS and allows the BDS to reconstruct the stream into a BDS-specific stream and deliver the BDS-specific stream to a plurality of users or user terminals. 
     Moreover, exemplary embodiments of the present invention may notify the start of stream delivery to a plurality of users or user terminals. 
     According to exemplary embodiments of the present invention, an SD or BDS receives a user report and reduces a reception error rate based on the user report. 
     While the invention has been shown and described with reference to a certain exemplary embodiment 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.