Methods for providing conditional access information to decoders in a packet-based multiplexed communications system

In a packet-based multiplexed communications system in which a plurality of different elementary streams are each segmented and inserted into respective transport packets that are then multiplexed to form a single transport stream for transmission to a plurality of different remote locations, each remote location employing a decoder, each decoder operating in accordance with one of a plurality of different conditional access systems, wherein different sets of conditional access information specific to each of the different conditional access systems must be provided to the remote locations, a method of providing the different sets of conditional access information to the remote locations comprising the steps of:

• a) for each of said conditional access systems:
• i) inserting a set of conditional access information specific to that conditional access system into a respective sequence of transport packets;
• ii) assigning a unique packet ID to the set of conditional access information and inserting the unique packet ID in a header section of each transport packet in the respective sequence;
• b) generating a conditional access table that specifies, for each of said different conditional access systems, the packet ID of the transport packets that carry the set of conditional access information specific to that conditional access system;
• and
• c) transmitting the conditional access table and the transport packets that carry each of the different sets of conditional access information to the remote location along with the transport packets that carry the different elementary streams,
• whereby a decoder at a remote location, which operates in accordance with one of said different conditional access systems, can employ the transmitted conditional access table to identify and extract the transport packets that carry the set of conditional access information specific to the conditional access system upon which that decoder operates.

In a packet-based multiplexed communications system wherein a plurality of different elementary streams are each segmented and inserted into respective transport packets that are assigned a unique packet ID and then multiplexed to form a single transport stream for transmission to a remote location, different combinations of said elementary streams defining a plurality of different programs, and wherein the elementary streams are separately and uniquely encrypted prior to transmission and, for each elementary stream, encryption related information necessary for decrypting that elementary stream is inserted into a respective sequence of transport packets also being assigned a unique packet ID, and further wherein a program map table is transmitted in the transport stream that specifies, for each of said different programs, the packet IDs of the transport packets that carry each of the elementary streams that comprise said each program, said program map table further specifying, for each elementary stream of each program, the packet ID of the transport packets that carry the encryption related information for that elementary stream, a method of accessing a selected program for output at a remote location comprising the steps of:

• a) receiving the transport stream at the remote location and retrieving the program map table from the received transport stream;
• b) identifying from the program map table the packet IDs of the transport packets that carry the elementary streams of the selected program, and also identifying from the program map table the packet IDs of the transport packets that carry the encryption related information necessary for decrypting each elementary stream of the selected program;
• c) extracting from the received transport stream the transport packets having the packet IDs identified in step (b) in order to retrieve and decrypt the elementary streams of the selected program for output at the remote location.

In a packet-based multiplexed communications system in which a plurality of transport packets are multiplexed to form a single transport stream for transmission to a plurality of different remote locations, each remote location employing a decoder and each decoder operating in accordance with one of a plurality of different conditional access systems, each conditional access system having a unique identifier (CA.sub.-- System.sub.-- ID) associated therewith and each decoder being provided with the CA.sub.-- System.sub.-- ID of the conditional access system in accordance with which it operates, and wherein, for each conditional access system, conditional access information specific to that conditional access system is transmitted to each remote location in a respective sequence of transport packets having a unique packet ID, and further wherein a conditional access table is transmitted in the transport stream that specifies, for each conditional access system operating in the communications system, the packet ID of the transport packets that carry the conditional access information specific to that conditional access system, a method of retrieving at a decoder the conditional access information specific to the conditional access system in accordance with which the decoder operates, said method comprising the steps of:

• a) receiving the transport stream at the remote location;
• b) accessing the conditional access table transmitted in the transport stream with the CA.sub.-- System.sub.-- ID provided to the decoder to identify the packet ID of the transport packets that carry conditional access information specific to the conditional access system of that decoder;
• and
• c) extracting from the transport stream the transport packets having the packet ID identified in step (b) in order to obtain the conditional access information specific to the conditional access system of the decoder.