Patent Publication Number: US-8532037-B2

Title: Method and apparatus for transmitting and receiving mobility information supporting handover and/or roaming in digital broadcasting system

Description:
PRIORITY 
     This application claims priority to Korean Patent Application Serial No. 10-2007-0006211 filed Jan. 19, 2007; and to International Application PCT/KR2008/000300 filed Jan. 17, 2008; the contents of each of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a digital broadcasting system, and more particularly to a method and an apparatus for transmitting/receiving mobility information to support the handover and roaming in a CBMS (Convergence of Broadcasting and Mobile Services) system. 
     2. Description of the Related Art 
     As generally known in the art, mobile broadcasts are recently provided by broadcasting systems or mobile communication systems in line with the development of communication and broadcasting technology. There are also discussions about mobile broadcasts that can transmit packet data through broadcasting channels, besides conventional broadcasting services that are limited to sounds and images. Mobile broadcasts are provided through a sequence of operations including the discovery of a service by a mobile terminal (e.g. mobile telephone, laptop computer, PDA) capable of receiving mobile broadcasts, subscription to the service by the mobile terminal, provision of various types of control information necessary to receive the service, transmission of the service, and reception of the service by the mobile terminal. 
     The OMA (Open Mobile Alliance) is one of the groups that are studying standards for the interworking between separate mobility solutions, and is mainly in charge of establishing various application standards regarding mobile games, Internet services, etc. One of the working groups of the OMA, particularly a sub-working group of the OMA BAC (Browse and Content) BCAST (Mobile Broadcast) is studying technology for the convergence of broadcasting and mobile services (CBMS) using mobile terminals capable of communicating with interactive networks. In addition, the DVB-CBMS (Digital Video Broadcasting-Convergence of Broadcasting and Mobile Services), one of the organizations for standards regarding mobile broadcasts based on mobile terminals, is defining the system structure, interface, etc., which are necessary for the CBMS. 
     In general, terminals adapted to receive broadcasting services in a mobile broadcasting system receive an ESG (Electronic Service Guide), which includes information regarding the service itself, billing, and method for receiving the service, and then receive a desired service by using the ESG. 
     When a terminal in a mobile broadcasting system moves from a home network (i.e. network of the home service provider to which the terminal user has subscribed) to a visited network (i.e. network of a foreign service provider), the user wants to receive broadcasting services from the home network or services from the foreign service provider, which has a roaming agreement with the home service provider, by using the terminal carried with him/her. This procedure is called roaming. When the terminal moves from the home network to the visited network while receiving a broadcasting service, the user wants to receive the broadcasting service seamlessly through the terminal. This procedure is called a handover. 
     However, conventional CBMS systems do not provide a definite procedure for the roaming and handover of broadcasting services. Therefore, technology for efficiently providing the roaming and handover of broadcasting services in a mobile broadcasting system is necessary. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and it is an aspect of the present invention to provide a method and an apparatus for transmitting information regarding the type and execution of a handover and roaming by using mobility information for supporting the handover and roaming of a terminal adapted to receive a broadcasting service. 
     It is another aspect of the present invention to provide a method and an apparatus for transmitting/receiving mobility information regarding a handover and roaming to support the handover and roaming in a CBMS system. 
     It is a further aspect of the present invention to provide a method and an apparatus for transmitting/receiving mobility information regarding a handover and roaming by using an ESG for broadcasting services, a notification message, or other signaling means. 
     In order to accomplish these aspects of the present invention, there is provided a method for transmitting handover-related information for a terminal in a CBMS system, the method including the steps of setting handover-related information including information elements for indicating at least one available handover type; inserting the handover-related information into an ESG regarding broadcasting services so that the handover-related information is transmitted to a terminal; and conducting handover of the terminal according to the handover-related information. 
     In accordance with another aspect of the present invention, there is provided a method for receiving handover-related information for a terminal in a CBMS system, the method including the steps of receiving an ESG regarding broadcasting services from a network; detecting handover-related information including information elements for indicating at least one available handover type from the ESG; and conducting handover of the terminal according to the handover-related information. 
     In accordance with a further aspect of the present invention, there is provided an apparatus for transmitting handover-related information for a terminal in a CBMS system, the apparatus including a handover control entity for setting handover-related information including information elements for indicating at least one available handover type; an ESG entity for inserting the handover-related information into an ESG regarding broadcasting services so that the handover-related information is transmitted to a terminal; and a mobility management block for conducting handover of the terminal according to the handover-related information. 
     In accordance with a still further aspect of the present invention, there is provided an apparatus for receiving handover-related information for a terminal in a CBMS system, the apparatus including a receiver for receiving an ESG regarding broadcasting services from a network; and a mobility management block for detecting handover-related information including information elements for indicating at least one available handover type from the ESG and conducting handover of the terminal according to the handover-related information. 
     The present invention is advantageous in that, by providing a terminal adapted to receive broadcasting services with mobility information necessary for the handover/roaming of the terminal by means of an ESG, a notification message, or other signaling means in advance, an efficient handover is supported. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other exemplary features, aspects, and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a block diagram showing a CBMS structure according to an exemplary embodiment of the present invention; 
         FIG. 2  shows a data model of an ESG according to an exemplary embodiment of the present invention; 
         FIGS. 3   a  and  3 B show types of indication by mobility information according to an exemplary embodiment of the present invention; 
         FIGS. 4   a  and  4   b  are flowcharts showing operations for transmitting mobility information according to an embodiment of the present invention; 
         FIG. 5  is a flowchart showing operations for receiving mobility information according to an embodiment of the present invention; 
         FIGS. 6   a  and  6   b  are flowcharts showing operations for transmitting mobility information according to another embodiment of the present invention; 
         FIG. 7  is a flowchart showing operations for receiving mobility information according to another embodiment of the present invention; 
         FIGS. 8   a  and  8   b  are flowcharts showing operations for transmitting mobility information according to a still another embodiment of the present invention; 
         FIG. 9  is a flowchart showing operations for receiving mobility information according to a still another embodiment of the present invention; 
         FIGS. 10   a  and  10   b  show examples of using an announcement carousel session to deliver mobility information according to an exemplary embodiment of the present invention; 
         FIGS. 11   a  and  11   b  show examples of using a bootstrap session to deliver mobility information according to an exemplary embodiment of the present invention; 
         FIG. 12  is a block diagram showing the structure of a network device according to an exemplary embodiment of the present invention; and 
         FIG. 13  is a block diagram showing the structure of a terminal device according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein is omitted to avoid making the subject matter of the present invention unclear. The terminology used herein is defined based on consideration of relevant functionality according to the present invention, and may vary depending on the intention or practice of the user or operator. Therefore, the definition must be understood based on the overall context of the specification. 
     The gist of the present invention will be described briefly. When a broadcast receiver (i.e. terminal) in a CBMS system moves from a home network to a visited network, or from the service region of a home service provider to that of a foreign service provider, mobility information regarding the handover and/or roaming (hereinafter, referred to as handover/roaming) is provided by the home service provider, which the terminal can access, before the handover or roaming occurs. 
       FIG. 1  is a block diagram showing the structure of a CBMS system according to an exemplary embodiment of the present invention. Particularly,  FIG. 1  shows logical entities for fulfilling functions necessary for the IPDC (Internet Protocol Data Cast) based on DVB-H (Digital Video Broadcasting-Handheld). The entities are separately shown according to the difference in major functions, and may be positioned in physically separated servers or in the same server. 
     Referring to  FIG. 1 , the CC (Content Creation) block  110  creates a content source of a broadcasting service and sends it to the SA (Service Application) block  120 . The SA block  120  aggregates contents from the CC block  110  and relevant metadata additionally needed for service configuration, and creates service data regarding a specific service. The SA block  120  encodes the contents in a format that the terminal can understand, and provides them by using either streaming or file carousel delivery. The SA block  120  creates service description metadata to be used by the ESG To this end, the SA block  120  includes a number of sub-entities for managing different applications for respective services of the IPDC. 
     The SM (Service Management) block  130  is adapted for service configuration, resource allocation, ESG provisioning, security, etc. between the SA block  120  and the terminal  160 . 
     The broadcasting network  140  refers to a network for transmitting broadcasting service data, such as a DVB-H system. The interactive network  150  refers to a conventional cellular mobile communication network, such as UMTS (Universal Mobile Telecommunications System) based on 3GPP (3 rd  Generation Partnership Project), IMT (International Mobile Telecommunications)-2000 based on 3GPP2, or Wibro (Wireless Broadband). Any type of network may constitute the interactive network  150 , as long as it can receive information or a request from the terminal  160  and transmit a response to the information or request. The broadcasting network  140  and the interactive network  150  function as transmission bearers in the CBMS system. The terminal  160  refers to user equipment, i.e. a receiver adapted to access the interactive network  150  and receive a broadcasting service from the broadcasting network  140 . In the CBMS system, the terminal  160  receives service data and signaling information from the broadcasting network, and interacts with the interactive network  150  to exchange service data and signaling information. 
     The interfaces between respective entities, including the above-mentioned logical entities, will now be described. 
     The interfaces X- 1 , X- 2 , and X- 3  correspond to reference points between the broadcasting network and different entities, and may be omitted in the case of an interactive standard based on DVB-H. Particularly, the interface X- 1  connects between the CC block  110  and the SA block  120 , the interface X- 2  connects between the interactive network  150  and the terminal  160 , and the interface X- 3  connects between the SM Block  130  and the interactive network  150 . 
     The interface CBMS- 1  delivers broadcasting-related signaling. The interface CBMS- 2  delivers contents such as audios, videos, files, etc. The interface CBMS- 3  delivers an ESG The interface CBMS- 4  delivers an ESG in a PtP (Point-to-Point) transmission type. The interface CBMS- 5  delivers an SMS (Short Message Service), an MMS (Multimedia Message Service), etc. in the PtP transmission type. The interface CBMS- 6  delivers configuration parameters, including the number of services, the allocated bandwidth, etc., for DVB-H transmission. The interface CBMS- 7  delivers a service application announcement or metadata. Those skilled in the art can understand that, although typical functions of respective interfaces have been described, this description does not limit the functionality of respective interfaces. 
       FIG. 2  shows a data model of an ESG according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 2 , respective blocks shown in the drawing correspond to fragments of ESG data. Particularly, the ESG data model includes a service fragment  202 , a schedule event fragment  204 , a content fragment  206 , an acquisition fragment  208 , a service bundle fragment  210 , a purchase fragment  212 , and a purchase channel fragment  214 . 
     The service fragment  202  contains an overall description of the service. The schedule event fragment  204  contains information regarding the service in terms of time. The acquisition fragment  208  contains service access information necessary to receive service data. The service bundle fragment  210  contains information regarding cases of combining different services into a service bundle. The purchase fragment  212  contains price information necessary to purchase the service bundle. The fragment channel fragment  214  contains information regarding a system necessary to acquire the right to purchase. 
     Each fragment of the data model can refer to other fragments, and the arrows between the fragments indicate such reference. As used herein, the reference means that the current fragment gives information regarding it by using information transmitted by other fragments. More particularly, when a service consists of different contents, the service fragment  202  contains an overall description of the service, such as the name and language of the service, but has no description of the contents transmitted in connection with the service. Instead, the content fragment  206  of the corresponding contents refers to the service fragment. In order to obtain various pieces of information necessary for the terminal to receive the service, such as information regarding the session used for the transmitted protocol, the acquisition fragment  208 , to which the service fragment  202  is referring, is received and decoded to obtain such information. 
     The ESG data is separately transmitted to the terminal by using at least one IP (Internet Protocol) stream at a time different from that at which the data stream is transmitted. Therefore, the service supplier can provide information, which the user needs to know before receiving the service, by using the ESG data model before transmission of the service. By receiving the ESG stream, the terminal can acquire information necessary to receive services from the service supplier. When the user selects a specific service, the terminal accesses a data stream, which transmits the service, by using the acquired information, and receives data. The information necessary for the terminal to access the service data stream is transmitted through the acquisition fragment  208 , as has been described with reference to  FIG. 1 . 
     The fragments of the ESG data model are grouped into a number of sets, which are contained in separate containers. Each container is considered as an object in the FLUTE (File Delivery over Unidirectional Transport protocol) session and is transmitted. 
     When a handover is necessary in the CBMS system, different types of handover can be used depending on different conditions. For example, either a passive handover or an active handover is used according to whether or not an interactive channel is available. In this case, either signaling or a service is delivered through the interactive channel according to whether signaling information or service data can be transmitted through the interactive channel. Furthermore, either a network control handover or a terminal control handover is used according to whether the network or the terminal decides the handover. 
     It is impossible for the terminal to know the entire handover/roaming procedure instantly without any preceding condition information, so it becomes necessary to communicate with the network to obtain information regarding the handover/roaming type (hereinafter, referred to as mobility information). Therefore, according to an exemplary embodiment of the present invention, the mobility information is added to an ESG regarding a broadcasting service. The terminal obtains the mobility information from the ESG before a handover actually occurs, and properly determines the point of time, at which the handover/roaming is necessary, and the handover/roaming type based on the mobility information and other condition information obtained from the ESG The following Table 1a discloses handover types, which the mobility information can indicate, together with their descriptions. 
     
       
         
           
               
             
               
                 TABLE 1a 
               
             
            
               
                   
               
               
                 (Handover types) 
               
            
           
           
               
               
               
            
               
                 No 
                 Handover type 
                 Description 
               
               
                   
               
               
                 1 
                 Passive handover 
                 1. Terminal control 
               
               
                 2 
                 Terminal control active 
                 Terminal control 
               
               
                   
                 handover with assistant 
                 Interactive network is available 
               
               
                   
                 signaling 
                 Terminal can acquire handover-related information over 
               
               
                   
                   
                 interactive network 
               
               
                   
                   
                 Interactive network type 
               
               
                 3 
                 Terminal control active 
                 Terminal control 
               
               
                   
                 handover with service delivery 
                 Interactive network is available 
               
               
                   
                 over interactive network 
                 Terminal can receive service over interactive network 
               
               
                   
                   
                 Interactive network type 
               
               
                 4 
                 Terminal control active 
                 Terminal control 
               
               
                   
                 handover with assistant 
                 Interactive network is available 
               
               
                   
                 signaling and service delivery 
                 Terminal can acquire handover-related information over 
               
               
                   
                 over interactive network 
                 interactive network 
               
               
                   
                   
                 Terminal can receive service over interactive network 
               
               
                   
                   
                 Interactive network type 
               
               
                 5 
                 Network control handover 
                 Network control 
               
               
                   
                   
                 Interactive network is available 
               
               
                   
                   
                 Network supports handover over interactive network 
               
               
                   
                   
                 Interactive network type 
               
               
                 6 
                 Network control handover with 
                 Network control 
               
               
                   
                 service delivery over interactive 
                 Interactive network is available 
               
               
                   
                 network 
                 Network supports handover over interactive network 
               
               
                   
                   
                 Service can be delivered to terminal over interactive network 
               
               
                   
                   
                 Interactive network type 
               
               
                 7 
                 Both terminal control and 
                 Both terminal control and network control are optional 
               
               
                   
                 network control handover are 
                 Interactive network is available 
               
               
                   
                 optional 
                 Network supports handover over interactive network 
               
               
                   
                   
                 Interactive network type 
               
               
                 8 
                 Both terminal control and 
                 Both terminal control and network control are optional 
               
               
                   
                 network control handover are 
                 Interactive network is available 
               
               
                   
                 optional with service delivery 
                 Network supports handover over interactive network 
               
               
                   
                 over interactive network 
                 Service can be delivered to terminal over interactive network 
               
               
                   
                   
                 Interactive network type 
               
               
                   
               
            
           
         
       
     
     In the case of roaming, various roaming types can be used depending on conditions similar to those of the handover. The following Table 1b discloses roaming types, which the mobility information can indicate, together with their descriptions. 
     
       
         
           
               
             
               
                 TABLE 1b 
               
             
            
               
                   
               
               
                 (roaming types) 
               
            
           
           
               
               
               
            
               
                 No 
                 Roaming type 
                 Description 
               
               
                   
               
               
                 1 
                 Passive roaming 
                 1. Terminal control 
               
               
                 2 
                 Terminal control active roaming 
                 Terminal control 
               
               
                   
                 with assistant signaling 
                 Interactive network is available 
               
               
                   
                   
                 Terminal can acquire roaming-related information over 
               
               
                   
                   
                 interactive network 
               
               
                   
                   
                 Interactive network type 
               
               
                 3 
                 Terminal control active roaming 
                 Terminal control 
               
               
                   
                 with service delivery over 
                 Interactive network is available 
               
               
                   
                 interactive network 
                 Terminal can receive service over interactive network 
               
               
                   
                   
                 Interactive network type 
               
               
                 4 
                 Terminal control active roaming 
                 Terminal control 
               
               
                   
                 with assistant signaling and 
                 Interactive network is available 
               
               
                   
                 service delivery over interactive 
                 Terminal can acquire roaming-related information over 
               
               
                   
                 network 
                 interactive network 
               
               
                   
                   
                 Terminal can receive service over interactive network 
               
               
                   
                   
                 Interactive network type 
               
               
                 5 
                 Network control roaming 
                 Network control 
               
               
                   
                   
                 Interactive network is available 
               
               
                   
                   
                 Network supports roaming over interactive network 
               
               
                   
                   
                 Interactive network type 
               
               
                 6 
                 Network control roaming with 
                 Network control 
               
               
                   
                 service delivery over interactive 
                 Interactive network is available 
               
               
                   
                 network 
                 Network supports roaming over interactive network 
               
               
                   
                   
                 Service can be delivered to terminal over interactive network 
               
               
                   
                   
                 Interactive network type 
               
               
                 7 
                 Both terminal control and 
                 Both terminal control and network control are optional 
               
               
                   
                 network control roaming are 
                 Interactive network is available 
               
               
                   
                 optional 
                 Network supports roaming over interactive network 
               
               
                   
                   
                 Interactive network type 
               
               
                 8 
                 Both terminal control and 
                 Both terminal control and network control are optional 
               
               
                   
                 network control roaming are 
                 Interactive network is available 
               
               
                   
                 optional with service delivery 
                 Network supports roaming over interactive network 
               
               
                   
                 over interactive network 
                 Service can be delivered to terminal over interactive network 
               
               
                   
                   
                 Interactive network type 
               
               
                   
               
            
           
         
       
     
     Those skilled in the art can easily understand that, although various types of handover/roaming are disclosed in Tables 1a and 1b, the present invention is also applicable to handover/roaming types other than those disclosed herein. In addition, detailed parameters and information elements related to the mobility information (described later) are variable depending on the system or service, to which they are applied, or other handover/roaming types. 
     The mobility information may directly indicate the handover/roaming type. Alternatively, the mobility information may combine and use at least one information element to indicate the handover/roaming type and information necessary to conduct the handover/roaming. 
       FIG. 3   a  shows a type of indication by mobility information according to an exemplary embodiment of the present invention. As shown, the mobility information  302  includes a first information element  304  indicating who controls the handover/roaming, a second information element  306  indicating whether or not signaling over the interactive network is available, and a third information element  308  indicating whether or not service delivery over the interactive network is available. Based on the received mobility information  302 , the terminal  312  decides what type of handover/roaming is to be conducted. 
       FIG. 3   b  shows a type of indication by mobility information according to another embodiment of the present invention. As shown, the mobility information  322  directly indicates what type of handover/roaming is to be conducted  324 . Based on the received mobility information  322 , the terminal  332  recognizes detailed conditions, including who controls the handover/roaming  334 , whether or not signaling over the interactive network is available  336 , and whether or not service delivery over the interactive network is available  338 . 
     The mobility information can be delivered by means of an ESG or a notification message, which is used in mobile broadcasting systems. Alternatively, independent signaling may be used to deliver the mobility information. Such a notification message is used to notify terminals of particulars of change in the service, contents, or operations in broadcasting systems. 
     In order to deliver the mobility information, for example, an EventType field is used in the header of the notification message (hereinafter, referred to as a notification header). The following Table 2a shows the content of the EventType field for indicating the handover type. 
     
       
         
           
               
             
               
                 TABLE 2a 
               
             
            
               
                   
               
               
                 (header of notification message) 
               
            
           
           
               
               
            
               
                 EventType 
                 Content 
               
               
                   
               
               
                 Handover 
                 Handover type: 
               
            
           
           
               
               
               
            
               
                   
                 1. 
                 terminal control handover 
               
            
           
           
               
               
               
            
               
                   
                 1.1. 
                 with service delivery over interactive network 
               
               
                   
                 1.2. 
                 without service delivery over interactive 
               
               
                   
                   
                 network 
               
            
           
           
               
               
               
            
               
                   
                 2. 
                 terminal control with network assistant 
               
            
           
           
               
               
               
            
               
                   
                 2.1. 
                 with service delivery over interactive network 
               
               
                   
                 2.2. 
                 without service delivery over interactive network 
               
            
           
           
               
               
               
            
               
                   
                 3. 
                 both terminal could network control are available 
               
            
           
           
               
               
               
            
               
                   
                 3.1. 
                 with service delivery over interactive network 
               
               
                   
                 3.2. 
                 without service delivery over interactive network 
               
            
           
           
               
               
               
            
               
                   
                 4. 
                 network control 
               
            
           
           
               
               
               
            
               
                   
                 4.1. 
                 with service delivery over interactive network 
               
               
                   
                 4.2. 
                 without service delivery over interactive network 
               
            
           
           
               
               
            
               
                   
                 Handover related information: 
               
               
                   
                 For example, if interactive network is available, its type, 
               
               
                   
                 provider, address and so on could be provided here. 
               
               
                   
                   
               
            
           
         
       
     
     The following Table 2b shows another embodiment of using some bits in the EventType field to indicate the handover type. 
     
       
         
           
               
             
               
                 TABLE 2b 
               
             
            
               
                   
               
               
                 (header of notification message) 
               
            
           
           
               
               
               
            
               
                   
                 Bits in 
                   
               
               
                 EventType 
                 content 
                 Description 
               
               
                   
               
               
                 Handover 
                 2 
                 00: terminal control 
               
               
                   
                   
                 01: network control 
               
               
                   
                   
                 10: both terminal and network control are available 
               
               
                   
                 1 
                 0: signaling over interactive network is not available 
               
               
                   
                   
                 1: signaling over interactive network is available 
               
               
                   
                 1 
                 0: service delivery over interactive network is not 
               
               
                   
                   
                 available 
               
               
                   
                   
                 1: service delivery over interactive network is 
               
               
                   
                   
                 available 
               
               
                   
               
            
           
         
       
     
     When the notification header of the notification message has no EventType field, handover/roaming-related information is directly indicated by the content of the notification message, as shown in the following Table 3a. 
     
       
         
           
               
             
               
                 TABLE 3a 
               
             
            
               
                   
               
               
                 (notification message) 
               
            
           
           
               
               
            
               
                   
                 Content 
               
               
                   
                   
               
            
           
           
               
               
            
               
                 Handover 
                 Handover type: 
               
            
           
           
               
               
               
            
               
                 information 
                 1. 
                 terminal control handover 
               
            
           
           
               
               
               
            
               
                 carried in 
                 1.1. 
                 with service delivery over interactive 
               
               
                 notification 
                 1.2. 
                 without service delivery over interactive 
               
               
                   
                   
                 network 
               
            
           
           
               
               
               
            
               
                   
                 2. 
                 terminal control with network assistant 
               
            
           
           
               
               
               
            
               
                   
                 2.1. 
                 with service delivery over interactive network 
               
               
                   
                 2.2. 
                 without service delivery over interactive 
               
               
                   
                   
                 network 
               
            
           
           
               
               
               
            
               
                   
                 3. 
                 both terminal could network control are available 
               
            
           
           
               
               
               
            
               
                   
                 3.1. 
                 with service delivery over interactive network 
               
               
                   
                 3.2. 
                 without service delivery over interactive 
               
               
                   
                   
                 network 
               
            
           
           
               
               
               
            
               
                   
                 4. 
                 network control 
               
            
           
           
               
               
               
            
               
                   
                 4.1. 
                 with service delivery over interactive network 
               
               
                   
                 4.2. 
                 without service delivery over interactive 
               
               
                   
                   
                 network 
               
            
           
           
               
               
            
               
                   
                 Handover related information: 
               
               
                   
                 For example, if interactive network is available, its type, 
               
               
                   
                 provider, address and so on could be provided here. 
               
               
                   
                   
               
            
           
         
       
     
     The following Table 3b shows another embodiment of using some bits in the notification message to indicate the handover type. 
     
       
         
           
               
             
               
                 TABLE 3b 
               
             
            
               
                   
               
               
                 (notification message) 
               
            
           
           
               
               
               
            
               
                   
                 Bits in 
                   
               
               
                   
                 content 
                 Description 
               
               
                   
                   
               
            
           
           
               
               
               
            
               
                 Handover 
                 2 
                 00: terminal control 
               
               
                 information 
                   
                 01: network control 
               
               
                 carried in 
                   
                 10: both terminal and network control are 
               
               
                 notification 
                   
                 available 
               
               
                   
                 1 
                 0: signaling over interactive network is not 
               
               
                   
                   
                 available 
               
               
                   
                   
                 1: signaling over interactive network is available 
               
               
                   
                 1 
                 0: service delivery over interactive network is not 
               
               
                   
                   
                 available 
               
               
                   
                   
                 1: service delivery over interactive network is 
               
               
                   
                   
                 available 
               
               
                   
               
            
           
         
       
     
     The following Table 4a shows a format when an independent signaling message (hereinafter, referred to as a handover signaling message) is used to deliver handover/roaming-related information. Particularly, the header of the handover signaling message indicates handover types. 
     
       
         
           
               
             
               
                 TABLE 4a 
               
             
            
               
                   
               
               
                 (handover signaling message) 
               
            
           
           
               
               
            
               
                 Header 
                 Content 
               
               
                   
               
               
                 Handover 
                 Handover type: 
               
            
           
           
               
               
               
            
               
                 signaling 
                 1. 
                 terminal control handover 
               
            
           
           
               
               
               
            
               
                   
                 1.1. 
                 with service delivery over interactive network 
               
               
                   
                 1.2. 
                 without service delivery over interactive network 
               
            
           
           
               
               
               
            
               
                   
                 2. 
                 terminal control with network assistant 
               
            
           
           
               
               
               
            
               
                   
                 2.1. 
                 with service delivery over interactive network 
               
               
                   
                 2.2. 
                 without service delivery over interactive network 
               
            
           
           
               
               
               
            
               
                   
                 3. 
                 both terminal could network control are available 
               
            
           
           
               
               
               
            
               
                   
                 3.1. 
                 with service delivery over interactive network 
               
               
                   
                 3.2. 
                 without service delivery over interactive network 
               
            
           
           
               
               
               
            
               
                   
                 4. 
                 network control 
               
            
           
           
               
               
               
            
               
                   
                 4.1. 
                 with service delivery over interactive network 
               
               
                   
                 4.2. 
                 without service delivery over interactive network 
               
            
           
           
               
               
            
               
                   
                 Handover related information: 
               
               
                   
                 For example, if interactive network is available, its type, 
               
               
                   
                 provider, address and so on could be provided here. 
               
               
                   
                   
               
            
           
         
       
     
     The following Table 4b shows another embodiment of using a handover signaling message to deliver handover/roaming-related information. Particularly, some bits in the handover signaling message indicate handover types. 
     
       
         
           
               
             
               
                 TABLE 4b 
               
             
            
               
                   
               
               
                 (handover signaling message) 
               
            
           
           
               
               
               
            
               
                   
                 Bits in 
                   
               
               
                 Header 
                 content 
                 Description 
               
               
                   
               
               
                 Handover 
                 2 
                 00: terminal control 
               
               
                 signaling 
                   
                 01: network control 
               
               
                   
                   
                 10: both terminal and network control are available 
               
               
                   
                 1 
                 0: signaling over interactive network is not available 
               
               
                   
                   
                 1: signaling over interactive network is available 
               
               
                   
                 1 
                 0: service delivery over interactive network is not 
               
               
                   
                   
                 available 
               
               
                   
                   
                 1: service delivery over interactive network is 
               
               
                   
                   
                 available 
               
               
                   
               
            
           
         
       
     
     The following Table 5a shows a format of mobility information added to the ESG according to a first embodiment of the present invention. Those skilled in the art can easily understand that, although handover-related information is solely shown for convenience of description, the ESG also contains roaming-related information in a similar format. The present invention is not limited to the details described below, and more related information can be added depending on the relevant standards, system design, and the needs of network operators. 
     
       
         
           
               
             
               
                 TABLE 5a 
               
               
                   
               
               
                 (handover-related information 1) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 &lt;element name=″Handover″&gt; 
               
               
                  &lt;complexType&gt; 
               
               
                  &lt;sequence&gt; 
               
               
                   &lt;element name=″HandoverControl″&gt; 
               
               
                   &lt;complexType&gt; 
               
               
                    &lt;complexContent&gt; 
               
               
                    &lt;extension base=″HandoverCotrolType″&gt; 
               
               
                     &lt;attribute name=″type″ type=″HandoverCotrolType″/&gt; 
               
               
                    &lt;/ extension&gt; 
               
               
                    &lt;/ complexContent&gt; 
               
               
                   &lt;/ complexType&gt; 
               
               
                   &lt;/ element&gt; 
               
               
                   &lt;element name=″InteractiveNetworkType″ type=″InteractiveNetwork″ minOccurs=″0″/&gt; 
               
               
                   &lt;element name=″RelatedMaterial″ type=″anyURI″ minOccurs=″0″/&gt; 
               
               
                  &lt;/ sequence&gt; 
               
               
                  &lt;attribute name=″SignalingOverInteractiveNetwork″ type=″xs:boolean″ use=″optional″/&gt; 
               
               
                  &lt;attribute  name=″ServiceDeliveryOverInteractiveNetworkHandover″  type=″  boolean″ 
               
               
                 use=“optional″/&gt; 
               
               
                  &lt;/ complexType&gt; 
               
               
                 &lt;/ element&gt; 
               
               
                 &lt;simpleType name=″HandoverCotrolType″&gt; 
               
               
                  &lt;restriction base=″string″&gt; 
               
               
                  &lt;enumeration value=″terminal control″/&gt; 
               
               
                  &lt;enumeration value=″both terminal and network control are optional″/&gt; 
               
               
                  &lt;enumeration value=″network control″/&gt; 
               
               
                  &lt;/ restriction&gt; 
               
               
                 &lt;/ simpleType&gt;&lt;complex Type name=”  handover ”  &gt; 
               
               
                  &lt;sequence&gt; 
               
               
                  &lt;element name=” HandoverControlType”  type=”  esg: HandoverControlType” &gt; 
               
               
                  &lt;element name=” InteractiveNetwork”  type=”  esg: InteractiveNetwork” &gt; 
               
               
                  &lt;element name=” RelatedMaterial”  type=”  anyURI” &gt; 
               
               
                  &lt;sequence&gt; 
               
               
                  &lt;attribute  name=” Signaling  over  interactive  network”  type=”  Boolean” 
               
               
                 use=” optional” /&gt; 
               
               
                  &lt;attribute name=” Service delivery over interactive network handover”  type=”  Boolean” 
               
               
                 use=” optional” /&gt; 
               
               
                 &lt;/complex type&gt; 
               
               
                   
               
            
           
         
       
     
     The following Table 5b shows another format of handover-related information contained in the ESG. 
     
       
         
           
               
             
               
                 TABLE 5b 
               
               
                   
               
               
                 (handover-related information 2) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 &lt;element name=“Handover”&gt; 
               
               
                  &lt;complexType&gt; 
               
               
                  &lt;sequence&gt; 
               
               
                  &lt;element name=“HandoverControl” type=“HandoverCotrolType”/&gt; 
               
               
                  &lt;element name=“InteractiveNetworkType” 
               
               
                  type=“InteractiveNetwork” minOccurs=“0”/&gt; 
               
               
                  &lt;element name=“RelatedMaterial” type=“anyURI” minOccurs=“0”/&gt; 
               
               
                  &lt;/ sequence&gt; 
               
               
                  &lt;attribute name=“SignalingOverInteractiveNetwork” 
               
               
                  type=“xs:boolean” use=“optional”/&gt; 
               
               
                  &lt;attribute  name=“ServiceDeliveryOverInteractiveNetworkHandover” 
               
               
                 type=“  boolean” use=“optional”/&gt; 
               
               
                  &lt;/ complexType&gt; 
               
               
                 &lt;/ element&gt; 
               
               
                 &lt;complexType name=“HandoverCotrolType”&gt; 
               
               
                  &lt;choice minOccurs=“0”/&gt; 
               
               
                  &lt;element name=“terminalControl” type=“string” fixed=“terminal 
               
               
                  control”/&gt; 
               
               
                  &lt;element name=“ BothTerminalAndNetworkControlAreOptional” 
               
               
                  type=“string” fixed=“ both 
               
               
                 terminal and network control are optional ”/&gt; 
               
               
                  &lt;element name=“networkControl” type=“string” fixed=“network 
               
               
                  control”/&gt; 
               
               
                  &lt;/choice&gt; 
               
               
                 &lt;/ complexType &gt; 
               
               
                   
               
            
           
         
       
     
     The following Table 5c shows a still another format of handover-related information contained in the ESG. 
     
       
         
           
               
             
               
                 TABLE 5c 
               
               
                   
               
               
                 (handover-related information 3) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 &lt;element name=“Handover”&gt; 
               
               
                  &lt;complexType&gt; 
               
               
                  &lt;sequence&gt; 
               
               
                   &lt;element name=“HandoverControl” type=“tva:ControlledTermType” 
               
               
                   minOccurs=“0”/&gt; 
               
               
                   &lt;element name=“InteractiveNetworkType” 
               
               
                   type=“InteractiveNetwork” minOccurs=“0”/&gt; 
               
               
                   &lt;element name=“RelatedMaterial” type=“anyURI” minOccurs=“0”/&gt; 
               
               
                  &lt;/ sequence&gt; 
               
               
                  &lt;attribute name=“SignalingOverInteractiveNetwork” 
               
               
                  type=“xs:boolean” use=“optional”/&gt; 
               
               
                  &lt;attribute  name=“ServiceDeliveryOverInteractiveNetworkHandover” 
               
               
                 type=“  boolean” use=“optional”/&gt; 
               
               
                  &lt;/ complexType&gt; 
               
               
                 &lt;/ element&gt; 
               
               
                   
               
            
           
         
       
     
     The information element “handover” in the above Tables 5a-5c represents handover-related information and includes information elements “HandoverControlType” and “InteractiveNetwork” (or “InteractiveNetworkType”). In addition, the information element “handover” includes optional attribute values “Signaling over interactive network” and “Service delivery over interactive network”. The information element “handover” may also include information element “RelatedMaterial” indicating the address of a server, from which additional handover-related information can be obtained, in the URL (Uniform Resource Locator) type. 
     The information element “HandoverControlType” is of the Boolean type, and designates the type of handover control. For example, it indicates that “terminal control handover is mandatory” or that “network control handover is mandatory”. In addition, the information element “HandoverControlType” may indicate that “both terminal and network control handover are optional”. The following Table 6 shows the detailed format of the “HandoverControlType”. 
     
       
         
           
               
             
               
                 TABLE 6 
               
               
                   
               
               
                 (handover control type) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 &lt;ClassificationScheme uri=“urn:dvb:ipdc:esg:cs:HandoverControlTypeCS:&gt; 
               
               
                 &lt;Term termID=“1.0”&lt;Name xml:lang=“en”&gt; Handover Control Type&lt;/Name&gt; 
               
               
                  &lt;Definition xml:lang=“en”&gt;Type of handover control, e.g. terminal control handover is mandatory, both 
               
               
                 terminal and network control handover are optional, network control handover is mandatory&lt;/Definition&gt; 
               
               
                  &lt;Term termID=“1.1&gt; 
               
               
                  &lt;Name xml:lang=“en”&gt; terminal control handover &lt;/Name&gt; 
               
               
                  &lt;Definition xml:lang=“en”&gt;A terminal control handover &lt;/Definition&gt; 
               
               
                 &lt;Term termID=“1.2&gt; 
               
               
                  &lt;Name xml:lang=“en”&gt; both terminal and network control handover are optional &lt;/Name&gt; 
               
               
                  &lt;Definition xml:lang=“en”&gt; both terminal and network control handover are optional &lt;/Definition&gt; 
               
               
                 &lt;Term termID=“1.3&gt; 
               
               
                  &lt;Name xml:lang=“en”&gt; network control handover &lt;/Name&gt; 
               
               
                  &lt;Definition xml:lang=“en”&gt;A network control handover &lt;/Definition&gt; 
               
               
                 &lt;ClassificationScheme uri=“urn:dvb:ipdc:esg:cs:MobilityCS”&gt; 
               
               
                  &lt;Term termID=“1”&gt; 
               
               
                  &lt;Name xml:lang=“en”&gt;HandoverCotrolType&lt;/Name&gt; 
               
               
                  &lt;Definitionxml:lang=“en”&gt;Type of handover control, e.g. terminal control handover is mandatory, 
               
               
                 both terminal and network control handover are optional, network control handover is mandatory 
               
               
                  &lt;/Definition&gt; 
               
               
                   &lt;Term termID=“1.1”&gt; 
               
               
                   &lt;Namexml:lang=“en”&gt; terminal control&lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt;A terminal control handover &lt;/Definition&gt; 
               
               
                   &lt;/Term&gt; 
               
               
                   &lt;Term termID=“1.2”&gt; 
               
               
                   &lt;Namexml:lang=“en”&gt; both terminal and network control are optional &lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt; both terminal and network control handover are optional &lt;/Definition&gt; 
               
               
                   &lt;/Term&gt; 
               
               
                   &lt;Term termID=“1.3”&gt; 
               
               
                   &lt;Namexml:lang=“en”&gt; network control&lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt;A network control handover &lt;/Definition&gt; 
               
               
                   &lt;/Term&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                 &lt;/ClassificationScheme&gt; 
               
               
                   
               
            
           
         
       
     
     The information element “InteractiveNetwork” designates the characteristics of the interactive network that supports a handover, and includes the URI (Uniform Resource Identifier) of the interactive network provider, the type of the interactive network, the acquisition reference which represents an access parameter, the IP address of the interactive network, and its port number. The information element “InteractiveNetwork” exists when the interactive network is available. 
     
       
         
           
               
             
               
                 TABLE 7a 
               
               
                   
               
               
                 (interactive network information) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 &lt;complexType name=“InteractiveNetwork”&gt; 
               
               
                  &lt;all&gt; 
               
               
                  &lt;element name=“InteractiveNetworkProvider” type=“InteractiveNetwork ProviderType”/&gt; 
               
               
                  &lt;element name=“InteractiveNetwork”&gt; 
               
               
                   &lt;complexType&gt; 
               
               
                   &lt;complexContent&gt; 
               
               
                    &lt;extension base=“InteractiveNetworkType”&gt; 
               
               
                    &lt;attribute name=“type” type=“InteractiveNetworkType”/&gt; 
               
               
                    &lt;/ extension&gt; 
               
               
                   &lt;/ complexContent&gt; 
               
               
                   &lt;/ complexType&gt; 
               
               
                  &lt;/ element&gt; 
               
               
                  &lt;element name=“AcquisitionRef” type=“anyURI”/&gt; 
               
               
                  &lt;element name=“interactiveNetworkIPAddress” type=“anyURI”/&gt; 
               
               
                  &lt;element name=“InteractiveNetworkPortNumber” type=“anyURI”/&gt; 
               
               
                  &lt;/ all&gt; 
               
               
                 &lt;/ complexType&gt; 
               
               
                 &lt;complexType name=“InteractiveNetworkProviderType”&gt; 
               
               
                  &lt;sequence&gt; 
               
               
                  &lt;element name=“ProviderURI” type=“anyURI”/&gt; 
               
               
                  &lt;element name=“ProviderName” type=“mpeg7:TextualType” minOccurs=“0”/&gt; 
               
               
                  &lt;element name=“ProviderLogo” type=“mpeg7:TitleMediaType” minOccurs=“0”/&gt; 
               
               
                  &lt;element name=“ProviderID” type=“positiveInteger” minOccurs=“0”/&gt; 
               
               
                  &lt;element name=“ProviderInformationURL” type=“anyURI” minOccurs=“0”/&gt; 
               
               
                  &lt;element name=“PrivateAuxiliaryData” type=“anyType” minOccurs=“0”/&gt; 
               
               
                  &lt;/ sequence&gt; 
               
               
                 &lt;/   complexType&gt;&lt;complex   Type   name=“interactive  network”minOccurs   = 
               
               
                 “0”maxOccurs=“unbounded”/&gt; 
               
               
                 &lt;all&gt; 
               
               
                  &lt;element name=“InteractiveNetworkProvider”type= “anyURIHandoverControlType”&gt; 
               
               
                  &lt;element name=“InteractiveNetwork” type=“esg: InteractiveNetworkType”&gt; 
               
               
                  &lt;element name=“AcquisitionRef”type=“anyURI”&gt; 
               
               
                  &lt;element name=“InteractiveNetworkIPAddress”type=“anyURI”&gt; 
               
               
                  &lt;element name=“InteractiveNetworkPortNumber”type=“anyURI”&gt; 
               
               
                  &lt;/all&gt; 
               
               
                 &lt;/complex type&gt; 
               
               
                   
               
            
           
         
       
     
     The “InteractiveNetworkType” specified by the information element “InteractiveNetwork” may be, for example, 3GPP, 3GPP2, WLAN (Wireless Local Area Network), WiBro (Wireless Broadband), etc. The following Table 7b enumerates a number of possible interactive network types. 
     
       
         
           
               
             
               
                 TABLE 7b 
               
               
                   
               
               
                 (interactive network types) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                   
                 &lt;simpleType name=“InteractiveNetworkType”&gt; 
               
               
                   
                  &lt;restriction base=“string”&gt; 
               
               
                   
                  &lt;enumeration value=“3GPP”/&gt; 
               
               
                   
                  &lt;enumeration value=“3GPP2”/&gt; 
               
               
                   
                  &lt;enumeration value=“WLAN”/&gt; 
               
               
                   
                  &lt;enumeration value=“WIBRO”/&gt; 
               
               
                   
                  &lt;/restriction&gt; 
               
               
                   
                 &lt;/simpleType&gt; 
               
               
                   
                   
               
            
           
         
       
     
     When the “Signaling over interactive network” in Table 5 is set to be “true”, it means that signaling over the interactive network is possible, and, when set to be “false”, it means that signaling over the interactive network is not possible. Similarly, when the “Service delivery over interactive network” is set to be “true”, it means that service data delivery over the interactive network is possible, and, when set to be “false”, it means that service data delivery over the interactive network is not possible. 
     According to another embodiment of the present invention, the mobility information is inserted into a service fragment of the ESG. The following Table 8a shows fields inserted into the service fragment in connection with the mobility information. 
     
       
         
           
               
               
             
               
                 TABLE 8a 
               
               
                   
               
               
                 Field name 
                 Meaning 
               
               
                   
               
             
            
               
                 HandoverControlType 
                 Indicates handover control type. For example, indicates if terminal 
               
               
                   
                 control handover is mandatory, if network control handover is 
               
               
                   
                 mandatory, or if terminal/network control handover is optional, etc. 
               
               
                 InteractiveNetwork 
                 Indicates interactive network characteristics. For example, 
               
               
                   
                 interactive network indictor, type, access parameter, etc. Exists only 
               
               
                   
                 if interactive network is available. 
               
               
                 RelatedMaterial 
                 Indicates reference information regarding handover-related 
               
               
                   
                 materials. For example, IP platform, information provider, service 
               
               
                   
                 identifier, signal frequency, cell information, etc. 
               
               
                 Signaling over 
                 If set to be “true”, it means that signaling over interactive network is 
               
               
                 interactive network 
                 possible; if set to be “false”, it means that signaling over interactive 
               
               
                   
                 network is not possible. 
               
               
                 Service delivery over 
                 If set to be “true”, it means that service data delivery over 
               
               
                 interactive network 
                 interactive network is possible; if set to be “false”, it means that 
               
               
                 handover 
                 service data delivery over interactive network is not possible. 
               
               
                   
               
            
           
         
       
     
     For example, the fields of the Table 8a have formats as shown in the following Table 8b. 
     
       
         
           
               
             
               
                 TABLE 8b 
               
               
                   
               
             
            
               
                 &lt;element name=“Handover”&gt; 
               
               
                  &lt;complexType&gt; 
               
               
                  &lt;sequence&gt; 
               
               
                   &lt;element name=“InteractiveNetworkType” type=“InteractiveNetwork” minOccurs=“0”/&gt; 
               
               
                   &lt;element name=“RelatedMaterial” type=“anyURI” minOccurs=“0”/&gt; 
               
               
                  &lt;/ sequence&gt; 
               
               
                  &lt;attribute name=“SignalingOverInteractiveNetwork” type=“xs:boolean” use=“optional”/&gt; 
               
               
                  &lt;attribute  name=“ServiceDeliveryOverInteractiveNetworkHandover”  type=“  boolean” 
               
               
                 use=“optional”/&gt; 
               
               
                  &lt;attribute name=“NetworkControlAbailabilty” type=“xs:boolean” use=“optional”/&gt; 
               
               
                  &lt;attribute name=“NetworkControlIsMandatory” type=“xs:boolean” use=“optional”/&gt; 
               
               
                  &lt;/s:complexType&gt; 
               
               
                  &lt;/ element&gt;&lt;complex Type name=“handover ” 
               
               
                  &lt;sequence&gt; 
               
               
                  &lt;element name=“InteractiveNetwork”type=“esg: InteractiveNetwork”&gt; 
               
               
                  &lt;element name=“RelatedMaterial” type=“anyURI”&gt; 
               
               
                  &lt;sequence&gt; 
               
               
                  &lt;attribute name=“signaling over interactive network” type=“Boolean” use=“optional”/&gt; 
               
               
                  &lt;attribute name=“service delivery over interactive network” type=“Boolean” use=“optional”/&gt; 
               
               
                  &lt;attribute name=“network control availability” type=“Boolean” use=“optional”/&gt; 
               
               
                  &lt;attribute name=“network control is mandatory” type=“Boolean” use=“optional”/&gt; 
               
               
                 &lt;/complex type&gt; 
               
               
                   
               
            
           
         
       
     
     The following Table 9 shows another format of handover-related information contained in the service fragment. 
     
       
         
           
               
               
             
               
                 TABLE 9 
               
               
                   
               
               
                 Field name 
                 Meaning 
               
               
                   
               
             
            
               
                 InteractiveNetwork 
                 Indicates interactive network characteristics. For example, interactive 
               
               
                   
                 network indictor, type, access parameter, etc. Exists only if interactive 
               
               
                   
                 network is available. 
               
               
                 RelatedMaterial 
                 Indicates reference information regarding handover-related materials. For 
               
               
                   
                 example, IP platform, information provider, service identifier, signal 
               
               
                   
                 frequency, cell information, etc. 
               
               
                 Signaling over 
                 If set to be “true”, it means that signaling over interactive network is 
               
               
                 interactive network 
                 possible; if set to be “false”, it means that signaling over interactive 
               
               
                   
                 network is not possible. 
               
               
                 Service delivery 
                 If set to be “true”, it means that service data delivery over interactive 
               
               
                 over interactive 
                 network is possible; if set to be “false”, it means that service data delivery 
               
               
                 network handover 
                 over interactive network is not possible. 
               
               
                 Network control 
                 If set to be “true”, it means that network control is possible; if set to be 
               
               
                 availability 
                 “false”, it means that network control is not possible. 
               
               
                 Network control is 
                 If set to be “true”, it means that network control is mandatory; if set to be 
               
               
                 mandatory 
                 “false”, it means that network control is not mandatory. 
               
               
                   
               
            
           
         
       
     
     Descriptions of the fields “InteractiveNetwork”, “Signaling over interactive network”, and “Service delivery over interactive network” in Tables 8a, 8b, and 9 are the same as those of the previous case. The additional attribute value “Network control availability” means that network control is available when set to be “true”, and that network control is not available when set to be “false”. Another attribute value “Network control is mandatory” means that network control is mandatory when set to be “true”, and that network control is not mandatory when set to be “false”. 
       FIGS. 4 and 5  are flowcharts showing operations of the network and the terminal according to a first embodiment of the present invention. As will be described below, the network-side operations are conducted by an entity that is in charge of handover control in the network, e.g. SA block  120 , SM block  130 , or other handover control entity. 
     Referring to  FIG. 4  (split into  FIG. 4   a  and  FIG. 4   b  for convenience), the network entity analyzes available handover mechanisms to set related information elements based on different handover mechanisms, for example, based on consideration of the capacity of terminals, the agreement with the interactive network, etc., in step  402 , and sets handover-related information in step  404 . For example, if an interactive network is available, the handover-related information includes information regarding the interactive network. The network entity determines if service delivery over the interactive network is possible in step  406 . If it is determined that service delivery over the interactive network is possible, the network entity sets the handover-related information element “service delivery over interactive network” to be “true” in step  408 . If not, the network entity sets the “service delivery over interactive network” to be “false” in step  410 . 
     The network entity checks at least one available handover mechanism in step  412  and proceeds to at least one of steps  414 ,  422 ,  430 , and  438 . If the network entity decides to set handover-related information regarding a passive handover mechanism in step  414 , the “Signaling over interactive network” is set to be “false” in step  416 , the “Network control availability” is set to be “false” in step  418 , and the “Network control is mandatory” is set to be “false” in step  420 . 
     If the network entity decides to set handover-related information regarding the mechanism of a network-supported terminal control handover in step  422 , the “Signaling over interactive network” is set to be “true” in step  424 , the “Network control availability” is set to be “false” in step  426 , and the “Network control is mandatory” is set to be “false” in step  428 . 
     If the network entity decides to set handover-related information regarding the mechanism of a handover controlled by both the terminal and the network in step  430 , the “Signaling over interactive network” is set to be “true” in step  432 , the “Network control availability” is set to be “true” in step  434 , and the “Network control is mandatory” is set to be “false” in step  436 . 
     If the network entity decides to set handover-related information regarding the mechanism of a network control handover in step  438 , the “Signaling over interactive network” is set to be “true” in step  440 , the “Network control availability” is set to be “true” in step  442 , and the “Network control is mandatory” is set to be “true” in step  444 . 
     After setting all information elements to be included in the handover-related information through steps  414 - 444 , the network entity inserts the handover-related information, which includes the above-mentioned information elements, into mobility information, loads the mobility information onto at least one ESG stream, and transmits it to terminals in step  450 . If a handover actually occurs, the network entity processes or manages the handover based on the handover-related information in step  452 . In the case of a passive handover, the network entity has nothing to do with the handover procedure. In the case of a handover controlled by both the terminal and the network, the network entity takes proper measures according to whether it is a terminal control handover or a network control handover. 
     Referring to  FIG. 5 , the terminal receives mobility information by means of at least one ESG stream provided by the CBMS system in step  502 . The terminal detects handover-related information included in the mobility information in step  504 . The terminal analyzes the information elements “HandoverControlType” and “InteractiveNetwork”, which are included in the handover-related information, based on a predetermined syntax of the handover-related information in step  506 . Particularly, based on the handover type confirmed from the “HandoverControlType”, the terminal determines if a terminal control handover is possible, if a network control handover is possible, or if both a terminal control handover and a network control handover are optional. 
     The terminal confirms that a terminal control handover is possible based on the “HandoverControlType” in step  508 . The terminal analyzes the “Signaling over interactive network” and “Service delivery over interactive network”, which are included in the handover-related information, in step  510 . The terminal determines if signaling over the interactive network is possible based on the “Signaling over interactive network” in step  512 . If signaling over the interactive network is not possible, the terminal decides to conduct a passive handover in step  516 . If signaling over the interactive network is possible, the terminal decides to conduct a network-supported passive handover, i.e. a terminal control handover with network support, in step  514 , and proceeds to step  530 . 
     The terminal confirms that both a terminal control handover and a network control handover are optional based on the “HandoverControlType” in step  518 . The terminal analyzes the “Signaling over interactive network” and “Service delivery over interactive network” in step  520 . If the “Signaling over interactive network” has been set to be “true”, the terminal decides to conduct a handover controlled by both the terminal and the network in step  522 , and proceeds to step  530 . 
     The terminal confirms that a network control handover is possible based on the “HandoverControlType” in step  524 . The terminal analyzes the “Signaling over interactive network” and “Service delivery over interactive network” in step  526 . If the “Signaling over interactive network” has been set to be “true”, the terminal decides to conduct a network control handover in step  528 , and proceeds to step  530 . 
     In step  530 , the terminal conducts a handover, if necessary, according to the handover mechanism, which has been confirmed to be available through steps  508 - 528 . If the “Service delivery over interactive network” has been set to be “true”, service data can be received over the interactive network after the handover is conducted. When the terminal decides a handover in step  530 , the terminal either decides a handover by itself or receives a handover instruction from the network according to whether the handover is controlled by the terminal or by the network. The handover decision is basically made by the terminal or by the network according to the intensity of signals received from the home network as measured by the terminal and/or the intensity of signals received from the visited network. 
       FIGS. 6 and 7  are flowcharts showing operations of the network and the terminal according to another embodiment of the present invention. 
     Referring to  FIG. 6  (split into  FIG. 6   a  and  FIG. 6   b  for convenience), the network entity analyzes available handover mechanisms to set related information elements based on different handover mechanisms in step  602 , and sets interactive network-related information, which is to be included in the handover-related information, in step  604 . In other words, if an interactive network is available, the handover-related information includes information regarding the interactive network, and related material information is set within the handover-related information. The network entity determines if service delivery over the interactive network is available in step  606 . If service delivery over the interactive network is possible, the handover-related information element “Service delivery over interactive network” is set to be “true” in step  608 . If service delivery over the interactive network is not possible, the “Service delivery over interactive network” is set to be “false” in step  610 . 
     The network entity checks at least one available handover mechanism in step  612  and proceeds to one of steps  614 ,  620 ,  626 , and  632 . If the network entity decides to set handover-related information regarding a passive handover mechanism in step  614 , the “HandoverControlType” is set to be “terminal control handover” in step  616 , and the “Signaling over interactive network” is set to be “false” in step  618 . 
     If the network entity decides to set handover-related information regarding the mechanism of a network-supported handover controlled by the terminal in step  620 , the “HandoverControlType” is set to be “terminal control handover” in step  622 , and the “Signaling over interactive network” is set to be “true” in step  624 . 
     If the network entity decides to set handover-related information regarding the mechanism of a handover controlled by both the terminal and the network in step  626 , the “HandoverControlType” is set to be “optional”, which means that both a terminal control handover and a network control handover are optional, in step  628 , and the “Signaling over interactive network” is set to be “true” in step  630 . 
     If the network entity decides to set handover-related information regarding the mechanism of a network control handover in step  632 , the “HandoverControlType” is set to be “network control handover” in step  634 , and the “Signaling over interactive network” is set to be “true” in step  636 . 
     After setting all information elements to be included in the handover-related information through steps  614 - 636 , the network entity inserts the handover-related information, which includes the above-mentioned information elements, into mobility information, loads the mobility information onto at least one ESG stream, and transmits it to terminals in step  640 . If a handover actually occurs, the network entity processes or manages the handover based on the handover-related information in step  642 . In the case of a passive handover, the network entity has nothing to do with the handover procedure. In the case of a handover controlled by both the terminal and the network, the network entity takes proper measures according to whether it is a terminal control handover or a network control handover. 
     Referring to  FIG. 7 , the terminal receives mobility information by means of at least one ESG stream provided by the CBMS system in step  702 . The terminal detects handover-related information included in the mobility information in step  704 . The terminal analyzes the information elements “HandoverControlType”, “RelatedMaterial”, and “InteractiveNetwork”, which are included in the handover-related information, based on a predetermined syntax of the handover-related information in step  706 . Particularly, based on the handover type confirmed from the “HandoverControlType”, the terminal determines if a terminal control handover is possible, if a network control handover is possible, or if both a terminal control handover and a network control handover are optional. 
     The terminal confirms that a terminal control handover is possible based on the “HandoverControlType” in step  708 . The terminal analyzes the “Signaling over interactive network” and “Service delivery over interactive network”, which are included in the handover-related information, in step  710 . The terminal determines if signaling over the interactive network is possible based on the “Signaling over interactive network” in step  712 . If signaling over the interactive network is not possible, the terminal decides to conduct a passive handover in step  716 . If signaling over the interactive network is possible, the terminal decides to conduct a network-supported passive handover, i.e. a terminal control handover with network support, in step  714 , and proceeds to step  730 . 
     The terminal confirms that both a terminal control handover and a network control handover are optional based on the “HandoverControlType” in step  718 . The terminal analyzes the “Signaling over interactive network” and “Service delivery over interactive network” in step  720 . If the “Signaling over interactive network” has been set to be “true”, the terminal decides to conduct a handover controlled by both the terminal and the network in step  722 , and proceeds to step  730 . 
     The terminal confirms that a network control handover is possible based on the “HandoverControlType” in step  724 . The terminal analyzes the “Signaling over interactive network” and “Service delivery over interactive network” in step  726 . If the “Signaling over interactive network” has been set to be “true”, the terminal decides to conduct a network control handover in step  728 , and proceeds to step  730 . 
     In step  730 , the terminal conducts a handover, if necessary, according to the decision made through steps  708 - 728 . If the “Service delivery over interactive network” has been set to be “true”, service data can be received over the interactive network after the handover is conducted. If necessary, the terminal acquires additional handover-related information from a server, which has been accessed based on the “RelatedMaterial” information, and uses the information to conduct the handover. When the terminal decides a handover in step  730 , the terminal either decides a handover by itself or receives a handover instruction from the network according to whether the handover is controlled by the terminal or by the network. The handover decision is basically made by the terminal or by the network according to the intensity of signals received from the home network as measured by the terminal and/or the intensity of signals received from the visited network. 
       FIGS. 8 and 9  are flowcharts showing operations of the network and the terminal according to another embodiment of the present invention. 
     Referring to  FIG. 8  (split into  FIG. 8   a  and  FIG. 8   b  for convenience), the network entity analyzes available handover mechanisms to set related information elements based on different handover mechanisms in step  802 , and sets interactive network-related information, which is to be included in the handover-related information, in step  804 . In other words, if an interactive network is available, the handover-related information includes information regarding the interactive network, and related material information is set within the handover-related information. The network entity determines if service delivery over the interactive network is available in step  806 . If service delivery over the interactive network is possible, the handover-related information element “Service delivery over interactive network” is set to be “true” in step  808 . If service delivery over the interactive network is not possible, the “Service delivery over interactive network” is set to be “false” in step  810 . 
     The network entity checks at least one available handover mechanism in step  812  and proceeds to one of steps  814 ,  822 ,  830 , and  838 . If the network entity decides to set handover-related information regarding a passive handover mechanism in step  814 , the “Signaling over interactive network” is set to be “false” in step  816 , the “Network control availability” is set to be “false” in step  818 , and the “Network control is mandatory” is set to be “false” in step  820 . 
     If the network entity decides to set handover-related information regarding the mechanism of a network-supported terminal control handover in step  822 , the “Signaling over interactive network” is set to be “true” in step  824 , the “Network control availability” is set to be “false” in step  826 , and the “Network control is mandatory” is set to be “false” in step  828 . 
     If the network entity decides to set handover-related information regarding the mechanism of a handover controlled by both the terminal and the network in step  830 , the “Signaling over interactive network” is set to be “true” in step  832 , the “Network control availability” is set to be “true” in step  834 , and the “Network control is mandatory” is set to be “false” in step  836 . 
     If the network entity decides to set handover-related information regarding the mechanism of a network control handover in step  838 , the “Signaling over interactive network” is set to be “true” in step  840 , the “Network control availability” is set to be “true” in step  842 , and the “Network control is mandatory” is set to be “true” in step  844 . 
     After setting all information elements to be included in the handover-related information through steps  814 - 844 , the network entity inserts the handover-related information, which includes the above-mentioned information elements, into mobility information, loads the mobility information onto at least one ESG stream, and transmits it to terminals in step  850 . If a handover actually occurs, the network entity processes or manages the handover based on the handover-related information in step  852 . In the case of a passive handover, the network entity has nothing to do with the handover procedure. In the case of a handover controlled by both the terminal and the network, the network entity takes proper measures according to whether it is a terminal control handover or a network control handover. 
     Referring to  FIG. 9 , the terminal receives mobility information by means of at least one ESG stream provided by the CBMS system in step  902 . The terminal detects handover-related information included in the mobility information in step  904 . The terminal analyzes the information elements “InteractiveNetwork”, “Service delivery over interactive network”, and “RelatedMaterial”, which are included in the handover-related information, based on a predetermined syntax of the handover-related information in step  906 . 
     The terminal analyzes the “Signaling over interactive network” in step  908 . If it is confirmed in step  910  that signaling over the interactive network is not possible, the terminal determines that a passive handover can be conducted in step  912 , and proceeds to step  928 . If it is confirmed that signaling over the interactive network is possible, the terminal proceeds to step  914  and analyzes the “Network control availability” included in the handover-related information. If it is confirmed in step  916  that network control is not available, the terminal determines that a network-supported passive handover can be conducted in step  918 , and proceeds to step  928 . If it is confirmed that network control is available, the terminal proceeds to step  920 . 
     The terminal analyzes the “Network control is mandatory” included in the handover-related information in step  920 . If it is confirmed in step  922  that network control is not mandatory, the terminal determines that a handover controlled by both the terminal and the network can be conducted in step  924 , and proceeds to step  924 . If it is confirmed that network control is mandatory, the terminal determines in step  926  that a network control handover can be conducted, and proceeds to step  928 . 
     In step  928 , the terminal conducts a handover, if necessary, according to the determined handover mechanism. If the “Service delivery over interactive network” has been set to be “true”, service data can be received over the interactive network after the handover is conducted. If necessary, the terminal acquires additional handover-related information from a server, which has been accessed based on the “RelatedMaterial” information, and uses the information to conduct the handover. When the terminal decides a handover in step  928 , the terminal either decides a handover by itself or receives a handover instruction from the network according to whether the handover is controlled by the terminal or by the network. The handover decision is basically made by the terminal or by the network according to the intensity of signals received from the home network as measured by the terminal and/or the intensity of signals received from the visited network. 
     Those skilled in the art can easily understand that, besides the above-mentioned formats of mobility information, other types of formats can also be used, as shown in the following Tables 10 and 11. 
     
       
         
           
               
             
               
                 TABLE 10 
               
               
                   
               
             
            
               
                 &lt;?xml version=“1.0” encoding=“UTF-8”?&gt; 
               
               
                 &lt;schema   xmlns:xs=“http://www.w3.org/2001/XMLSchema”   elementFormDefault=“qualified” 
               
               
                 attributeFormDefault=“unqualified”&gt; 
               
               
                  &lt;ClassificationScheme uri=“urn:dvb:ipdc:esg:cs:MobilityCS”&gt; 
               
               
                  &lt;Term termID=“1”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt;HandoverCotrolType&lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt;Type of handover control, e.g. terminal control handover is mandatory, 
               
               
                 both terminal and network control handover are optional, network control handover is mandatory 
               
               
                   &lt;/Definition&gt; 
               
               
                  &lt;Term termID=“1.1”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt; terminal control&lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt;A terminal control handover &lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                   &lt;Term termID=“1.2”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt; both terminal and network control are optional &lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt; both terminal and network control handover are optional &lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;Term termID=“1.3”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt; network control&lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt;A network control handover &lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;Term termID=“2”&gt; 
               
               
                  &lt;Name xml:lang=“en”&gt;HandoverType&lt;/Name&gt; 
               
               
                  &lt;Definition xml:lang=“en”&gt;HandoverType&lt;/Definition&gt; 
               
               
                  &lt;Term termID=“2.1”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt;Passive handover&lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt;1. terminal control&lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;Term termID=“2.2”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt; 
               
               
                   Terminal control Active handover with assistant signaling 
               
               
                  &lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt; 
               
               
                   1. terminal control 
               
               
                   2. Interactive network is available. 
               
               
                   3. the terminal could get handover assistant from network side over interactive network 
               
               
                   4. interactive network type 
               
               
                   &lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;Term termID=“2.3”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt; 
               
               
                   Terminal control active handover with service delivery over interactive network 
               
               
                   &lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt; 
               
               
                   1. terminal control 
               
               
                   2. Interactive network is available. 
               
               
                   3. the terminal could receive service over interactive network 
               
               
                   4. interactive network type 
               
               
                   &lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;Term termID=“2.4”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt; 
               
               
                   Terminal control active handover with assistant signaling and service delivery over interactive 
               
               
                 network 
               
               
                   &lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt; 
               
               
                   1. terminal control 
               
               
                   2. Interactive network is available. 
               
               
                   3. the terminal could get handover assistant from network side over interactive network 
               
               
                   4. the terminal could receive service over interactive network 
               
               
                   5. interactive network type 
               
               
                   &lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;Term termID=“2.5”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt; 
               
               
                   Network control handover 
               
               
                   &lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt; 
               
               
                   1. network control 
               
               
                   2. Interactive network is available. 
               
               
                   3. the network could assistant the terminal for handover over interactive network 
               
               
                   4. interactive network type 
               
               
                   &lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;Term termID=“2.6”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt; 
               
               
                   Network control with service delivery over interactive network handover 
               
               
                   &lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt; 
               
               
                   1. network control 
               
               
                   2. Interactive network is available. 
               
               
                   3. the network could assistant the terminal for handover over interactive network 
               
               
                   4. the service could delivered to the terminal over interactive network. 
               
               
                   5. interactive network type 
               
               
                   &lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;Term termID=“2.7”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt; 
               
               
                   Both terminal control and network control handover are optional 
               
               
                   &lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt; 
               
               
                   1. both terminal and network control are optional. 
               
               
                   2. Interactive network is available. 
               
               
                   3. the network could assistant the terminal for handover over interactive network 
               
               
                   4. interactive network type 
               
               
                   &lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;Term termID=“2.8”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt; 
               
               
                   Both terminal control and network control are optional with service delivery over interactive network 
               
               
                 handover 
               
               
                   &lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt; 
               
               
                   1. both terminal and network control are optional. 
               
               
                   2. Interactive network is available. 
               
               
                   3. the network could assistant the terminal for handover over interactive network 
               
               
                   4. the service could delivered to the terminal over interactive network 
               
               
                   5. interactive network type 
               
               
                   &lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;Term termID=“3”&gt; 
               
               
                  &lt;Name xml:lang=“en”&gt;RoamingType&lt;/Name&gt; 
               
               
                  &lt;Definition xml:lang=“en”&gt;RoamingType&lt;/Definition&gt; 
               
               
                  &lt;Term termID=“2.1”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt;Passive roaming&lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt;1. terminal control&lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;Term termID=“2.2”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt; 
               
               
                   Terminal control Active roaming with assistant signaling 
               
               
                   &lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt; 
               
               
                   1. terminal control 
               
               
                   2. Interactive network is available. 
               
               
                   3. the terminal could get handover assistant from network side over interactive network 
               
               
                   4. interactive network type 
               
               
                   &lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;Term termID=“2.3”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt; 
               
               
                   Terminal control active roaming with service delivery over interactive network 
               
               
                   &lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt; 
               
               
                   1. terminal control 
               
               
                   2. Interactive network is available. 
               
               
                   3. the terminal could receive service over interactive network 
               
               
                   4. interactive network type 
               
               
                   &lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;Term termID=“2.4”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt; 
               
               
                   Terminal control active handover with assistant signaling and service delivery over interactive 
               
               
                 network 
               
               
                   &lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt; 
               
               
                   1. terminal control 
               
               
                   2. Interactive network is available. 
               
               
                   3. the terminal could get roaming assistant from network side over interactive network 
               
               
                   4. the terminal could receive service over interactive network 
               
               
                   5.   interactive network type 
               
               
                   &lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;Term termID=“2.5”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt; 
               
               
                   Network control roaming 
               
               
                   &lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt; 
               
               
                   1. network control 
               
               
                   2. Interactive network is available. 
               
               
                   3. the network could assistant the terminal for roaming over interactive network 
               
               
                   4. interactive network type 
               
               
                   &lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;Term termID=“2.6”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt; 
               
               
                   Network control with service delivery over interactive network roaming 
               
               
                   &lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt; 
               
               
                   1. network control 
               
               
                   2. Interactive network is available. 
               
               
                   3. the network could assistant the terminal for roaming over interactive network 
               
               
                   4. the service could delivered to the terminal over interactive network. 
               
               
                   5. interactive network type 
               
               
                   &lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;Term termID=“2.7”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt; 
               
               
                   Both terminal control and network control roaming are optional 
               
               
                   &lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt; 
               
               
                   1. both terminal and network control are optional. 
               
               
                   2. Interactive network is available. 
               
               
                   3. the network could assistant the terminal for roaming over interactive network 
               
               
                   4. interactive network type 
               
               
                   &lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;Term termID=“2.8”&gt; 
               
               
                   &lt;Name xml:lang=“en”&gt; 
               
               
                   Both terminal control and network control are optional with service delivery over interactive network 
               
               
                 roaming 
               
               
                   &lt;/Name&gt; 
               
               
                   &lt;Definition xml:lang=“en”&gt; 
               
               
                   1. both terminal and network control are optional. 
               
               
                   2. Interactive network is available. 
               
               
                   3. the network could assistant the terminal for roaming over interactive network 
               
               
                   4. the service could delivered to the terminal over interactive network 
               
               
                   5. interactive network type 
               
               
                   &lt;/Definition&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;/Term&gt; 
               
               
                  &lt;/ClassificationScheme&gt; 
               
               
                 &lt;/schema&gt; 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 11 
               
               
                   
               
             
            
               
                 &lt;?xml version=“1.0” encoding=“UTF-8”?&gt; 
               
               
                 &lt;schema   xmlns:xs=“http://www.w3.org/2001/XMLSchema”   elementFormDefault=“qualified” 
               
               
                 attributeFormDefault=“unqualified”&gt; 
               
               
                  &lt;element name=“HandoverType”&gt; 
               
               
                  &lt;complexType&gt; 
               
               
                   &lt;choice&gt; 
               
               
                   &lt;element name=“PassiveHandover” minOccurs=“0”&gt; 
               
               
                    &lt;complexType&gt; 
               
               
                    &lt;attribute       name=“      type” type=“tva:ControlledTermType” 
               
               
                 fixed=“urn:dvb:ipdc:esg:cs:MobilityCS:2.1”/&gt; 
               
               
                    &lt;attribute  name=“HandoverControlType”  type=“HandoverCotrolType”  fixed=“terminal 
               
               
                 control”/&gt; 
               
               
                    &lt;/ complexType&gt; 
               
               
                   &lt;/ element&gt; 
               
               
                   &lt;element name=“TerminalControlActiveHandover WithAssistantSignaling” minOccurs=“0”&gt; 
               
               
                    &lt;complexType&gt; 
               
               
                    &lt;attribute       name=“type”       type=“tva:ControlledTermType” 
               
               
                 fixed=“urn:dvb:ipdc:esg:cs:MobilityCS:2.2”/&gt; 
               
               
                    &lt;attribute  name=“HandoverControlType”  type=“HandoverCotrolType”  fixed=“terminal 
               
               
                 control”/&gt; 
               
               
                    &lt;attribute name=“InterativeNetwork” type=“ boolean” fixed=“true”/&gt; 
               
               
                    &lt;attribute  name=“SignalingOverInteractiveNetwork”  type=“  boolean”  use=“optional” 
               
               
                 fixed=“true”/&gt; 
               
               
                    &lt;attribute name=“InteractiveNetworkType” type=“InteractiveNetworkType”/&gt; 
               
               
                    &lt;/ complexType&gt; 
               
               
                   &lt;/ element&gt; 
               
               
                   &lt;element  name=“TerminalControlActiveHandoverWithServiceDilivery  OverInteractiveNetwork” 
               
               
                 minOccurs=“0”&gt; 
               
               
                    &lt;complexType&gt; 
               
               
                    &lt;attribute       name=“type”       type=“tva:ControlledTermType” 
               
               
                 fixed=“urn:dvb:ipdc:esg:cs:MobilityCS:2.3”/&gt; 
               
               
                    &lt;attribute  name=“HandoverControlType”  type=“HandoverCotrolType”  fixed=“terminal 
               
               
                 control”/&gt; 
               
               
                    &lt;attribute name=“InterativeNetwork” type=“ boolean” fixed=“true”/&gt; 
               
               
                    &lt;attribute  name=“ServiceDeliveryOverInteractiveNetwork  Handover”  type=“  boolean” 
               
               
                 use=“optional” fixed=“true”/&gt; 
               
               
                    &lt;attribute name=“InteractiveNetworkType” type=“InteractiveNetworkType”/&gt; 
               
               
                    &lt;/ complexType&gt; 
               
               
                   &lt;/ element&gt; 
               
               
                   &lt;element           name=“TerminalCotrolActiveHandoverWithAssistant 
               
               
                 SignalingAndServiceDeliveryOverInteractiveNetwork” minOccurs=“0”&gt; 
               
               
                    &lt;complexType&gt; 
               
               
                    &lt;attribute       name=“type”       type=“tva:ControlledTermType” 
               
               
                 fixed=“urn:dvb:ipdc:esg:cs:MobilityCS:2.4”/&gt; 
               
               
                    &lt;attribute  name=“HandoverControlType”  type=“HandoverCotrolType”  fixed=“terminal 
               
               
                 control”/&gt; 
               
               
                    &lt;attribute name=“InterativeNetwork” type=“ boolean” fixed=“true”/&gt; 
               
               
                    &lt;attribute  name=“SignalingOverInteractiveNetwork”  type=“  boolean”  use=“optional” 
               
               
                 fixed=“true”/&gt; 
               
               
                    &lt;attribute  name=“ServiceDeliveryOverInteractiveNetwork  Handover”  type=“  boolean” 
               
               
                 use=“optional” fixed=“true”/&gt; 
               
               
                    &lt;attribute name=“InteractiveNetworkType”type= “InteractiveNetworkType”/&gt; 
               
               
                    &lt;/ complexType&gt; 
               
               
                   &lt;/ element&gt; 
               
               
                   &lt;element name=“NetworkCotrolHandover” minOccurs=“0”&gt; 
               
               
                    &lt;complexType&gt; 
               
               
                    &lt;attribute       name=“type”       type=“tva:ControlledTermType” 
               
               
                 fixed=“urn:dvb:ipdc:esg:cs:MobilityCS:2.5”/&gt; 
               
               
                    &lt;attribute name=“HandoverControlType” type=“HandoverCotrolType” fixed=“network control”/&gt; 
               
               
                    &lt;attribute name=“InterativeNetwork” type=“ boolean” fixed=“true”/&gt; 
               
               
                    &lt;attribute  name=“SignalingOverInteractiveNetwork”  type=“  boolean”  use=“optional” 
               
               
                 fixed=“true”/&gt; 
               
               
                    &lt;attribute name=“InteractiveNetworkType” type=“InteractiveNetworkType”/&gt; 
               
               
                    &lt;/ complexType&gt; 
               
               
                   &lt;/ element&gt; 
               
               
                   &lt;element  name=“NetworkCotrol  WithServiceDeliveryOver  InteractiveNetworkHandover” 
               
               
                 minOccurs=“0”&gt; 
               
               
                    &lt;complexType&gt; 
               
               
                    &lt;attribute       name=“type”       type=“tva:ControlledTermType” 
               
               
                 fixed=“urn:dvb:ipdc:esg:cs:MobilityCS:2.6”/&gt; 
               
               
                    &lt;attribute name=“HandoverControlType” type=“HandoverCotrolType” fixed=“network control”/&gt; 
               
               
                    &lt;attribute name=“InterativeNetwork” type=“ boolean” fixed=“true”/&gt; 
               
               
                    &lt;attribute  name=“SignalingOverInteractiveNetwork”  type=“  boolean”  use=“optional” 
               
               
                 fixed=“true”/&gt; 
               
               
                    &lt;attribute  name=“ServiceDeliveryOverInteractiveNetworkHandover”  type=“  boolean” 
               
               
                 use=“optional” fixed=“true”/&gt; 
               
               
                    &lt;attribute name=“InteractiveNetworkType” type=“InteractiveNetworkType”/&gt; 
               
               
                    &lt;/ complexType&gt; 
               
               
                   &lt;/ element&gt; 
               
               
                   &lt;element    name=“BothTerminalControlAndNetworkControl    HandoverAreOptional” 
               
               
                 minOccurs=“0”&gt; 
               
               
                    &lt;complexType&gt; 
               
               
                    &lt;attribute       name=“type”       type=“tva:ControlledTermType” 
               
               
                 fixed=“urn:dvb:ipdc:esg:cs:MobilityCS:2.7”/&gt; 
               
               
                    &lt;attribute name=“HandoverControlType” type=“HandoverCotrolType” fixed=“both terminal and 
               
               
                 network control are optional”/&gt; 
               
               
                    &lt;attribute name=“InterativeNetwork” type=“ boolean” fixed=“true”/&gt; 
               
               
                    &lt;attribute  name=“SignalingOverInteractiveNetwork”  type=“  boolean”  use=“optional” 
               
               
                 fixed=“true”/&gt; 
               
               
                    &lt;attribute name=“InteractiveNetworkType” type=“InteractiveNetworkType”/&gt; 
               
               
                    &lt;/ complexType&gt; 
               
               
                   &lt;/ element&gt; 
               
               
                   &lt;element           name=“BothTerminalControlAndNetworkControlAreOptional 
               
               
                 WithServiceDeliveryOverInteractiveNetworkHandover” minOccurs=“0”&gt; 
               
               
                    &lt;complexType&gt; 
               
               
                    &lt;attribute       name=“type”       type=“tva:ControlledTermType” 
               
               
                 fixed=“urn:dvb:ipdc:esg:cs:MobilityCS:2.8”/&gt; 
               
               
                    &lt;attribute name=“HandoverControlType” type=“HandoverCotrolType” fixed=“both terminal and 
               
               
                 network control are optional”/&gt; 
               
               
                    &lt;attribute name=“InterativeNetwork” type=“ boolean” fixed=“true”/&gt; 
               
               
                    &lt;attribute  name=“SignalingOverInteractiveNetwork”  type=“  boolean”  use=“optional” 
               
               
                 fixed=“true”/&gt; 
               
               
                    &lt;attribute  name=“ServiceDeliveryOverInteractiveNetworkHandover”  type=“  boolean” 
               
               
                 use=“optional” fixed=“true”/&gt; 
               
               
                    &lt;attribute name=“InteractiveNetworkType” type=“InteractiveNetworkType”/&gt; 
               
               
                    &lt;/ complexType&gt; 
               
               
                   &lt;/ element&gt; 
               
               
                   &lt;/ choice&gt; 
               
               
                  &lt;/ complexType&gt; 
               
               
                  &lt;/ element&gt; 
               
               
                  &lt; simpleType name=“HandoverCotrolType”&gt; 
               
               
                  &lt;restriction base=“ string”&gt; 
               
               
                   &lt;enumeration value=“terminal control”/&gt; 
               
               
                   &lt;enumeration value=“both terminal and network control are optional”/&gt; 
               
               
                   &lt;enumeration value=“network control”/&gt; 
               
               
                  &lt;/ restriction&gt; 
               
               
                  &lt;/ simpleType&gt; 
               
               
                  &lt;simpleType name=“InteractiveNetworkType”&gt; 
               
               
                  &lt;restriction base=“ string”&gt; 
               
               
                   &lt;enumeration value=“3GPP”/&gt; 
               
               
                   &lt;enumeration value=“3GPP2”/&gt; 
               
               
                   &lt;enumeration value=“WLAN”/&gt; 
               
               
                   &lt;enumeration value=“WIBRO”/&gt; 
               
               
                  &lt;/ restriction&gt; 
               
               
                  &lt;/ simpleType&gt; 
               
               
                 &lt;/ schema&gt; 
               
               
                   
               
            
           
         
       
     
     The position of mobility information in the basic data model of the ESG, as shown in  FIG. 2 , is variously determined as in the following descriptions. 
     1. ESG Fragment 
     When an ESG is used to deliver mobility information, the mobility information is added as a new information element to at least one of the service fragment  202 , the content fragment  206 , and the acquisition fragment  208 , which have been described with reference to  FIG. 2 . Alternatively, the mobility information is added as a new fragment (e.g. handover fragment) within the ESG. 
     2. ESG Announcement Carousel Session 
     In order to receive an ESG, the terminal identifies the IP address of the ESG bootstrap FLUTE (File Delivery over Unidirectional Transport protocol) session from the PSI/SI (Program Specific Information/Service Information), which is a control channel signal of the broadcasting system. The bootstrap session plays the role of providing basic information regarding the ESG, i.e. information regarding the ESG provider, the ESG list provided by the corresponding ESG provider, etc. These pieces of information are transmitted from an ESG provider discovery descriptor and an ESG access descriptor, respectively. Particularly, the ESG access descriptor informs of the IP address of the announcement carousel FLUTE session of each ESG. Each ESG has its own announcement carousel session, which plays the role of transmitting the ESG and providing brief information regarding the structure. 
       FIGS. 10 and 10   b  show examples of using an announcement carousel session to transfer mobility information. Referring to  FIG. 10   a , the announcement carousel session  1002  carries an ESG initialization container  1004  and a number of ESG index containers. The ESG initialization container  1004  includes an initialization message  1006  containing the compression mode of following ESG containers and related parameters, and mobility information  1008  having a format as described above. Referring to  FIG. 10   b , the mobility information  1014  is delivered by means of an independent ESG attribute container  1012 , which is carried by the announcement carousel session  1010 . 
     3. ESG Bootstrap 
     Before accessing the ESG announcement carousel session, the terminal acquires mobility information by means of an ESG bootstrap session  1102 , which carries basic information regarding the ESG, as shown in  FIG. 11   a . If an independent ESG bootstrap session exists for each IP platform, the mobility information may be indicated with regard to each ESG, each ESG provider, or each IP platform. 
     3.1 Mobility Information Regarding Each ESG 
     Mobility information regarding each ESG is either added to an ESG access descriptor  1106  and/or an ESG provider discovery descriptor  1104 , which are transmitted by means of the ESG bootstrap session  1102 , or recorded in a new independent descriptor  1108 . 
     3.2. Mobility Information Regarding Each ESG Provider 
     Mobility information regarding each ESG provider is added to the ESG provider discovery descriptor  1104  on the ESG bootstrap session  1102 , or to the independent descriptor  1108 . 
     3.3. Mobility Information Regarding Each IP Platform 
     Mobility information regarding each IP platform is added to the independent descriptor  1108  or to the PSI/SI signal. 
     According to an alternative embodiment, as shown in  FIG. 11   b , the mobility information is recorded in a descriptor  1122 , which is transmitted by means of a FLUTE session  1120  different from the existing ESG bootstrap session  1112 . The same or additional mobility information may be transmitted by an ESG provider discovery descriptor  1114  and/or an ESG access descriptor  1116  on the ESG bootstrap session  1112 . 
       FIG. 12  shows the structure of a network according to an exemplary embodiment of the present invention. For convenience,  FIG. 12  solely shows entities for conducting logical functions in the SM of the visited and home networks in connection with the exemplary embodiment of the present invention. 
     Referring to  FIG. 12 , the SA block  1204  aggregates relevant metadata and broadcasting contents from a number of sources in order to provide a specific service, and creates service data. The SA block  1204  encodes the service data in a format that the terminal  1220  can understand, and provides the terminal  1220  with it by using either streaming or file carousel delivery. The SA block  1204  creates metadata including a service description to be used for the ESG. 
     Inside the SM block  1208 , there exist an ESG entity  1242 , a service configuration &amp; resource allocation entity  1244 , a security/service protection provision entity  1246 , and an MM (Mobility Management) block  1240 . The ESG entity  1242  is adapted to create an ESG based on the metadata from the SA block  1204  and transmit it. The ESG includes mobility information in the above-mentioned format in order to support the handover and/or roaming of the terminal  1220 . If the ESG for transmitting the mobility information is replaced with another means (e.g. notification message or independent signaling message), the SM block  1208  or the SA block  1204  includes a transmission entity for inserting the mobility information into the message and transmitting it. 
     The service configuration &amp; resource allocation entity  1244 , which is adapted for service configuration and network resource allocation, communicates with the SA block  1204  to contend the bandwidth of the broadcast bearer. In addition, the service configuration &amp; resource allocation entity  1244  allocates services at a location on the broadcasting network topology, or determines the service bandwidth, and schedules the service time. The security/service protection provision entity  1246  is in charge of security, authentication, service protection, and service provision. These entities  1242 - 1246  are connected with the MM block  1240  to conduct functions necessary for the handover and roaming. The MM block  1240  conducts tasks related to the mobility of the terminal  1220 , particularly the handover and roaming. 
       FIG. 13  shows the structure of a terminal receiver according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 13 , the receiver  1300  has not only a broadcast receiver  1302  capable of receiving broadcasting signals from the broadcasting network, but also an interactive adaptor  1304  capable of accessing the interactive network. The broadcast receiver  1302  receives service data or signaling information from the broadcasting network. The interactive adaptor  1304  exchanges service data or signaling information with the interactive network. The MM block  1308  interworks with the MM block  1204  of the network to process the above-mentioned operations regarding the handover and roaming. 
     At least one of the devices  1302  and  1304  receives an ESG, detects mobility information of the above-mentioned format, and sends the mobility information to the MM block  1308 . The MM block  1308  is connected with a subscription management block  1310 , which is in charge of the management/acquisition of the right of the terminal regarding service subscription and the decryption of service contents, as well as with a content consumption block  1312  for providing the user with audios and videos in connection with the broadcasting service, and processes handover/roaming-related operations. 
     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.