| 摘要 |
The problem with transferring a multicast service to a television environment, or other environment without a return connection, is how the service provider receives the information about receivers willing to receive the service and how the multicast router can query the receiver sets as to whether they want to receive. The problem is solved by choosing one of the servers within the scope of influence of the querying multicast router to be an order server. The receiver sets, without return connections, notify the server of the services they want to receive, and likewise notify when they no longer want to receive the service. The notifications to the server can be made via a modem connection through a fixed network, for instance using a Web form. The next time the server makes the query about receivers willing to receive the service, the order server will reply on behalf of the receiver set. In this case, the multicast router routes the desired services to the transmission system of the television operator's broadcasting network, which then adds the packets to the multiplexed transmission of the general broadcast. The receiving set will in turn receive the broadcast, recognize the service by its identifying data and separate the service packets from the multiplexed transmission.
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