Abstract: A cable television system provides conditional access to services. The cable television system includes a headend from which service “instances”, or programs, are broadcast and a plurality of set top units for receiving the instances and selectively decrypting the instances for display to system subscribers. The service instances are encrypted using public and/or private keys provided by service providers or central authorization agents. Keys used by the set tops for selective decryption may also be public or private in nature, and such keys may be reassigned at different times to provide a cable television system in which piracy concerns are minimized.

Abstract: A cable television system provides conditional access to services. The cable television system includes a headend from which service “instances”, or programs, are broadcast and a plurality of set top units for receiving the instances and selectively decrypting the instances for display to system subscribers. The service instances are encrypted using public and/or private keys provided by service providers or central authorization agents. Keys used by the set tops for selective decryption may also be public or private in nature, and such keys may be reassigned at different times to provide a cable television system in which piracy concerns are minimized.

Abstract: Two additional structures for addition to the Digital Video Broadcasters (DVB) Service Information (SI) for implementation of the MPEG-2 Systems Standard (ISO/IEC 13818-1) are provided: the Logical Channel Table (LCT) and the Composite Channel Table (CCT). The LCT provides the mapping between a Logical Channel Number (LCN) representing a service and the transport stream(TSID)/program number (PN) on which the service can be found. LCT entries may designate either simple conventional channels or Composite Channels. The LCT contains a Composite Channel Indicator (CCI), which when set to ‘1’, indicates that the selected channel is a composite channel. In this case, the LCT entry gives the home channel of the Composite Channel, which provides the CCT to the decoder so that the tuner can be retuned to the actual program designated in the CCT for current viewing.

Abstract: A cable television system provides conditional access to services. The cable television system includes a headend from which service "instances", or programs, are broadcast and a plurality of set top units for receiving the instances and selectively decrypting the instances for display to system subscribers. The service instances are encrypted using public and/or private keys provided by service providers or central authorization agents. Keys used by the set tops for selective decryption may also be public or private in nature, and such keys may be reassigned at different times to provide a cable television system in which piracy concerns are minimized.

Abstract: An encryption control system to process an input transport data stream into an output transport data stream includes an input demultiplexer, a first secure microprocessor, a second secure microprocessor and an output multiplexer. The input transport data stream includes first entitlement managment message data. The input demultiplexer culls the first entitlement managment message data from the input transport data stream, the first entitlement management message data including an encrypted multi-session key. The first secure microprocessor processes the first entitlement management message data to recover the multi-session key by decrypting the encrypted multi-session key using a first algorithm. The second secure microprocessor re-encrypts the multi-session key using a second algorithm and formats second entitlement management message data based on the first entitlement management message data with the re-encrypted multi-session key substituted for the encrypted multi-session key.

Abstract: Two additional structures for addition to the Digital Video Broadcasters (DVB) Service Information (SI) for implementation of the MPEG-2 Systems Standard (ISO/IEC 13818-1 are provided: the Logical Channel Table (LCT) and the Composite Channel Table (CCT). The LCT provides the mapping between a Logical Channel Number (LCN) representing a service and the transport stream/program number on which the service can be found. LCT entries may designate either simple conventional channels or Composite Channels. The LCT contains a Composite Channel Indicator (CCI), which when set to `1`, indicates that the selected channel is a composite channel. In this case, the LCT entry gives the home channel of the Composite Channel, which provides the CCT to the decoder so that the tuner can be retuned to the actual program designated in the CCT for current viewing. Each entry in the CCT associates a Composite Channel Number (CCN) with a LCN and represents the "present" definition for the composite channel.

Abstract: A digital video, audio and data distribution system which enables a set-top terminal (STT) associated with a customer's television set or other information presentation device to request interactive digital video, audio and data services from a service provider (SP) through the use of control system messages transmitted via a hi-directional signalling path. The requested interactive service is transmitted from the service provider over a portion of the bandwidth of a broadband transmission network which is dedicated to interactive digital services. A Video Session Connection (VSC) is provided for setting up and maintaining interactive sessions between the set-top terminal and a video service provider during the time the interactive programming is provided to the customer. The set-top terminal and service provider establish the Video Session Connection via a two-way signalling path within the bandwidth of the transmission medium into the customer's home.

Abstract: Packets of data, some of which may carry a timestamp value, are transmitted through an Asynchronous Transfer Mode (ATM) network. Prior to transmission, each packet of data is encapsulated in a respective convergence sublayer protocol data unit (CS-PDU) having a header portion and a payload portion. The header portion of each CS-PDU contains a time correction indicator (TCI), which indicates whether the CS-PDU carries a packet of data having a timestamp value that may require correction after the CS-PDU passes through the network, and a time reference correction (TRC) field. Each CS-PDU is then segmented into a plurality of successive segments; a first one of the segments of each CS-PDU contains the CS-PDU header. Each segment is then inserted into the payload section of a respective ATM cell for transmission through the network. At each node in the network, cells are examined to determine if they contain a CS-PDU header.

Abstract: A method is disclosed for providing packet error indication in a multi-hop communications system in which packets of data are transmitted from a transmission site to a reception site via a plurality of successive physical links. According to the method, at the transmission site, a pre-defined bit in a packet to be transmitted is set to a first value, the first value indicating that no errors are present in the packet. Then, at each successive physical link in the communication system, after transmission of the packet over that physical link, the following steps are performed: (a) detecting whether any uncorrectable errors occurred in the packet during transmission over that physical link; (b) if an uncorrectable error is detected, setting the pre-defined bit in the packet to a second value wherein the second value is indicative of an uncorrectable error in the data of the packet; and (c) relaying the packet to the next successive physical link for transmission over that next link.

Abstract: In a packet-based multiplexed communications system, a method of providing different sets of conditional access information to a remote location comprises the steps of: (a) for each different set of conditional access information, inserting the set of conditional access information into a respective sequence of transport packets and assigning a unique packet ID to the transport packet of that sequence; (b) generating a table that specifies, for each of the different sets of conditional access information, the packet ID of the transport packets that carry that set of conditional access information; and (c) transmitting the table and the transport packets that carry each of the different sets of conditional access information to the remote location along with other information bearing transport packets. A decoder at the remote location can employ the transmitted table to identify and extract the transport packets that carry a selected one of the sets of conditional access information.

Abstract: Methods and apparatus are disclosed for providing virtual service selection in a multi-service communications system wherein the service components of each of a number of basic services are transmitted to subscriber locations on one of a plurality different frequency channels. Each frequency channel may carry the service components of more than one basic service. A virtual service definition is generated for each basic service that specifies which of the service components carried on a particular frequency channel comprise that service. The virtual service definition for each basic service is periodically, and frequently, transmitted to each subscriber location on the frequency channel carrying the service components that comprise that basic service.

Abstract: A plurality of digital services are carried in a multiplex data stream to a plurality of remote locations. The multiplex data stream comprises a continuous sequence of frames. Each frame comprises two consecutive fields, and each field comprises a plurality of lines. A first group of the lines in each field defines a transport layer region of that field, and a second group of the lines defines a service data region. Portions of the service data region of each field are allocated to respective ones of the video services in proportion to respective data rates of each service. A multiplex control packet is generated for each field that specifies, for each service, which portion of the service data region is allocated to that service. The multiplex control packet for each field is inserted into the transport layer region of that field along with a plurality of other packets that contain system related information.

Abstract: Methods and apparatus are described for uniquely encrypting a plurality services at a transmission site and for decrypting selected services at a reception site while reducing the amount of encryption related information that must be transmitted to the reception site for decryption purposes. A unique spreading function is generated at the transmission site for each service to be transmitted. A random quantity is then transmitted, and the random quantity is convolved with each spreading function to produce a unique encryption seed for each service. At least a portion of each service is then encrypted using the unique encryption seeds produced for each service. Only the random quantity is transmitted to the reception site along with the encrypted portions of each service. None of the unique encryption seeds are transmitted. At the reception site, the unique spreading functions generated at the transmission site for each service are regenerated.

Abstract: An apparatus providing a dynamic virtual service capability in a multi-service communications system is claimed. A dynamic virtual service comprises an associated group of basic services wherein only one of the basic services in the group is active at any time. Basic services comprise a number of service components which are transmitted to the apparatus on one or more of a plurality of different frequency channels. The apparatus comprises a service selection switch for selecting either one of the basic services directly or one of the dynamic virtual services. A dynamic virtual service map is provided that defines for each dynamic virtual service, on a time-varying basis, the currently active one of the group of basic services that comprise that dynamic virtual service. Means responsive to the service selection switch and to the dynamic virtual service map are provided for automatically selecting the currently active basic service of a subscriber selected dynamic virtual service.

Abstract: In a data transmission system comprising a plurality N of transmission sites and at least one reception site, a set of data at each transmission site is uniquely encrypted by (a) providing each transmission site with a broadcast key unique to that transmission site and a system key that is the same for all transmission sites, the system key comprising a plurality S of bits and each of the broadcast keys comprising a unique plurality B of bits, wherein B is less than S; (b) convolving in a predetermined manner at each transmission site the system key and the broadcast key unique to that transmission site to generate a unique data encryption key for that transmission site; (c) encrypting the set of data at each transmission site with the unique data encryption key generated at that site. The sets of data uniquely encrypted at each transmission site are then transmitted to the reception site.

Abstract: A system and method for multiplexing a plurality of digital programs for transmission to a plurality of remote locations is claimed. An encoder is provided that first generates a plurality of subframe data streams each comprising a continuous sequence of subframes. Each subframe in each subframe data stream comprises at least a transport layer region and a program data region. For each subframe data stream, portions of the program data region of each of the subframes in that subframe data stream are allocated to selected ones of the plurality of programs. Mapping information is provided in the transport layer region of each subframe for use by a decoder in extracting a selected program from each subframe. A multiplex data stream is then generated at the encoder that comprises a continuous sequence of superframes. Each superframe comprises a superframe transport layer region and a subframe data region.

Abstract: A method of transferring a data message from a remote unit to a central location is provided. A plurality of data channels is selected for transmitting the data message from the remote unit to the central location. At least one random transmit time is generated for transmitting the data message for each of the plurality of data channels. The data message is transmitted over the plurality of data channels at the transmit times. An apparatus for transferring a data message from a remote unit to a central location is also provided.

Abstract: Automatic level calibration apparatus for transmitting data from a cable television terminal to the headend of a cable television system comprises programmable transmitter apparatus of the terminal, programmable receiving apparatus at the headend and a calibration controller. Responsive to an addressed command from the headend, the programmable transmitter apparatus returns a sequence of levels at a particular calibration frequency. The programmable receiver apparatus determines an indication of the received signal strength of each of the levels of the sequence of levels. The controller determines an optimum level for transmissions from the terminal.