286 results about "Cable modem termination system" patented technology

A technique is described which may be used to synchronize a plurality of different access controllers which control a plurality of distinct ports at the Head End of an access network. In the context of a cable network, the technique of the present invention may be used to synchronize desired upstream and / or downstream channels across different line cards within a Cable Modem Termination System (CMTS). The technique involves utilizing a master time reference device which maintains and updates a current time reference, and periodically distributes synchronization signals to desired line cards in the system in order to synchronize these line cards. In a specific embodiment, the synchronization signals include current timestamp data generated from the master time reference device and distributed to all (or selected) line cards in the system. A slave time reference device on each of the line cards receives the periodic synchronization updates and uses the synchronization data to remain synchronized with the master time reference device. There are also provisions in this protocol to allow for hot insertion and removal of line cards, software reset or loading of the master and / or slave time reference devices, and redundant master time reference devices, including master time reference device fault detection and automatic fail over.

A method and system for load balancing in a network system such as a data-over-cable system. One method includes receiving a first message on a first network device such as a cable modem termination system (“CMTS”) from a second network device and marking the first message with an identifier of a network access device. The method further includes intercepting the first message on a third network device such as a provisioning / access manager prior to any first protocol server such a Dynamic Host Configuration Protocol server receives the first message. When the third network device intercepts the first message, the third network device determines capabilities of the second network device and applies a set of rules to load balance any requests between a plurality of channel pairs. Each charmel pair is associated with at least one capability of a network device and also has a load factor parameter and a threshold value defining a capacity of a channel pair. The third network device assigns the second network device to a predetermined channel pair based on the capabilities of the second network device, a load factor of the channel pair and a capacity of the channel pair.

A cable modem termination system is disclosed with flexible mapping of upstreams to downstreams and flexible mapping of downstreams to optical nodes and optical nodes to upstream receivers and the ability to add singe upstreams or downstreams as needed for load balancing. Multiple downstreams can share the same upstream. Multiple receivers can be coupled to the same upstream. Monitoring of upstream performance for overperforming or underperforming modems can be carried out, and new upstreams with higher and / or lower throughtput can be created to service the overperformers and / or underperformers. Modems can be grouped into logical groups with different performance levels and serviced by different upstreams or different upstream logical channels on the same upstream physical channel. An upstream linecard with a digital crosspoint switch is disclosed with the switch operated during contention intervals to allow reception with or without aggregation of noise where multiple upstream share the same receiver.

An upstream line card including a digital or analog multiplexer front end circuit for a Cable Modem Termination System. Each upstream line card has only upstream receivers and allows a CMTS to share one or a handful of receiver chips to receive and recover data from a larger number of input cables coupled to the front end multiplexer. A control circuit for the multiplexer uses MAP data and burst assignment data and upstream mini-slot counts for each of the input cables to determine when a burst is about to arrive on a cable and cause appropriate switching by the multiplexer or crossbar switch. In some embodiments, there is only one RF channel circuit coupled to the output of the multiplexer, so the multiplexer is controlled to couple the input cable upon which the burst is expected to the single RF channel. In other embodiments, there are multiple RF channels coupled to the inputs of the multiplexer so the multiplexer is controlled to connect each input cable on which a burst is expected to an available RF channel. In some embodiments, the sample data generated by each RF channel is buffered and an arbiter picks one burst at a time for application to the input of a CMTS receiver or doles out bursts to different receivers. In other embodiments, no buffers or arbiter are used, and each RF channel has its own dedicated CMTS receiver.

A distributed CMTS in a hybrid fiber / coaxial (HFC) plant. The distributed CMTS comprises at least one network layer, at least one media access control layer, and one or more physical layers. The at least one network layer, at least one media access control layer and one or more physical layers each function as separate modules, enabling them to be in separate locations, yet physically connected, throughout the HFC plant.

A cable modem communicates the timing of the arrival of certain packets (such as TCP ACK packets) to a cable modem termination system. This timing feature is useful in methods for increasing the throughput in the downstream direction by eliminating TCP ACKs backing up at a cable modem. In particular, a cable modem termination system implementing an unsolicited bandwidth grant service in which unsolicited grants of bandwidth are sent by the cable modem termination system to the cable modem. The grants of bandwidth are timed to arrive at the cable modem simultaneous with or shortly after the arrival of the TCP ACK from an end station connected to the cable modem. Several methods of calculating or predicting when the unsolicited grants should be sent to the cable modem are described. The method is also applicable to other types of packets, such as voice packets from a end station implementing a Voice over Internet Protocol (VoIP) application.

A modular Cable Modem Termination System (CMTS) includes a packet shelf operating a Data Over Cable Service Interface Specifications (DOCSIS) Media Access Control (MAC) framer. One or more downstream Physical Interface (PHY) shelves receive DOCSIS data from the packet shelf over a packet switched network and modulate the DOCSIS data for sending on a downstream path of a cable plant. One or more upstream PHY shelves send DOCSIS data received from an upstream path of the cable plant over the packet switched network to the packet shelf. By separating the PHY components from the MAC and from the system software, the PHY components for a Hybrid Fiber Coax (HFC) plant may be replaced with different PHY components for other access technologies such as wireless, Digital Subscriber Lines (DSL), Ethernet-to-the-Home, Fiber-to-the-Home, or fiber Passive Optical Networks (PONs).

Some embodiments of the present invention may include a method to stream packets into a queue for an upstream transmission, send multiple requests for upstream bandwidth to transmit data from the queue and receiving multiple grants to transmit data, and transmit data from the queue to the upstream as grants are received. Another embodiment may provide a network comprising a cable modem termination system (CMTS), and a cable modem wherein the cable modem may transmit data to the CMTS with a streaming protocol that sends multiple requests for upstream bandwidth to transmit data and receives multiple grants to transmit data, and transmits data to the CMTS as grants are received.

A cable modem termination system is disclosed with flexible mapping of upstreams to downstreams and flexible mapping of downstreams to optical nodes and optical nodes to upstream receivers and the ability to add singe upstreams or downstreams as needed for load balancing. Multiple downstreams can share the same upstream. Multiple receivers can be coupled to the same upstream. Monitoring of upstream performance for overperforming or underperforming modems can be carried out, and new upstreams with higher and / or lower throughtput can be created to service the overperformers and / or underperformers. Modems can be grouped into logical groups with different performance levels and serviced by different upstreams or different upstream logical channels on the same upstream physical channel.

A modular Cable Modem Termination System (CMTS) includes a packet shelf operating a Data Over Cable Service Interface Specifications (DOCSIS) Media Access Control (MAC) framer. One or more downstream Physical Interface (PHY) shelves receive DOCSIS data from the packet shelf over a packet switched network and modulate the DOCSIS data for sending on a downstream path of a cable plant. One or more upstream PHY shelves send DOCSIS data received from an upstream path of the cable plant over the packet switched network to the packet shelf. By separating the PHY components from the MAC and from the system software, the PHY components for a Hybrid Fiber Coax (HFC) plant may be replaced with different PHY components for other access technologies such as wireless, Digital Subscriber Lines (DSL), Ethernet-to-the-Home, Fiber-to-the-Home, or fiber Passive Optical Networks (PONs).

A system for testing a cable network during normal operation interleaves test signals with live data traffic. Installed cable modems are used to generate the test signals. During live communication, such modems send upstream data at allotted time periods. Periodically, there are time slots when no modem is transmitting on the network. During these times, specific modems may be directed to transmit specific test signals. A controller such as a cable modem termination system directs specific modems to transmit signals at defined frequencies and powers during specific time slots. In this manner, the system can monitor the frequency response of the cable network at various locations, and thereby determine “on-the-fly” when maintenance or modification is required.

A method of incorporating allocations of network access in a DOCSIS 1.0 compliant cable network, wherein users compete for bandwidth, includes limiting bandwidth consumed by a cable modem of a user to a value representative of that user's bandwidth allocation for a time interval. Preferably, the method includes the steps of: (a) generating cable modem configuration files, each of which limits bandwidth consumption by a cable modem of a user to a bandwidth allowance of that user equaling to the respective bandwidth allocation; (b) sending the configuration files to a Trivial File Transfer Protocol (TFTP) Server of the DOC Network; and (c) sending a command either to each user's cable modem, or to a cable modem termination system to which each user's cable modem is connected, to cause the cable modem to implement the respective new configuration file.

The present invention teaches methods and systems for subscriber blocking of unauthorized network traffic in a cable data network. The cable modem termination system (CMTS) incorporates a data gateway agent that filters unauthorized traffic thereby eliminating consumption based subscribers from being responsible for related service charges. Embodiments incorporate the use of packet filtering, hybrid stateful packet filtering, content filtering, application layer filtering and time based filtering. Greater acceptance of consumption based billing is achieved by having the filter settings directed by the subscriber.

The present invention enables the self-diagnosis functionality by embedding a cable modem with the CMTS system with mechanisms to redirect the signals from external connections to the embedded cable modem, thereby enabling the end user to fully test the CMTS using a suite of diagnostic tests. The embedded cable modem integrates the external CM, computer and diagnostic software in the chassis, or alternatively onto the CMTS card in the chassis. The invention enables the end user to fully test the functionality as a stand-alone unit, without relying on any external test equipment or methods. It also enables the end user to diagnose the CMTS from a remote location. Another major advantage of the present invention is that it enables the CMTS / CM function to be verified over the entire physical layer parameter set (frequency, symbol rate, FEC, signal levels, etc.) while not interrupting any of the services that are on the ‘live’ HFC plant.

A method and system for dynamic service registration, activation and deactivation on a data-over-cable system. A first network device, such as a cable modem with associated service devices (e.g., Voice over Internet Protocol telephones) sends a first message to another network device, such as a cable modem termination system. The first message includes multiple service parameters for a desired service requested by a service device associated with the first network device. The multiple service parameters are extracted from the first message. A service session profile is created for the desired service. The service session profile includes one or more of the extracted service parameters required by the desired service. The service session profile is used by a service server associated with the cable modem termination system to provide a desired service. The service session profile is associated with a deferred inactive service identifier for the cable modem. The deferred inactive service identifier is returned to the cable modem in a second message. The deferred inactive service identifier is used at a later time by a service device associated with the cable modem to activate the desired service and to generate a service event on a service server. The service event may include an authentication, authorization, accounting or other event. A deferred service can be activated and deactivated used even after a network device, such as a cable modem, has already established a session with another network device, such as a cable modem termination system, on a data-over-cable system.

A system and method is provided for scheduling transmissions from a plurality of services operating over a widely distributed communications network. A headend communications device (such as a cable modem termination system) arbitrates bandwidth among a plurality of cable modems configurable for bi-directional communications. The headend grants a bandwidth region to a specified cable modem or assigns contention regions for a group of cable modems. Each cable modem contains a local scheduler that sends requests for bandwidth according to local policies or rules. Upon receipt of a grant from the headend, the local scheduler selects packets to be transmitted to best serve the needs of the services associated with the cable modem. Accordingly, a service requesting bandwidth may not be the service utilizing the grant corresponding to bandwidth request. Nonetheless, the local scheduler manages bandwidth allocation among its local services such that all requesting services eventually receive bandwidth.

A cable network includes a Data Over Cable Service Interface Specifications (DOCSIS) set-top gateway (DSG) server connected to an Internet Protocol (IP) network and a DSG client operating in a set-top device connected to a cable network. A DSG agent operates in a cable modem termination system (CMTS) coupled between the IP network and the cable network. The DSG agent receives data from the DSG server and sends the data to the DSG client over dynamically assigned DSG tunnels.

A method and apparatus for controlling traffic loading on a cable modem termination system helps provide viable quality of service (QoS) capability on a cable data system. Available data bandwidth on a particular channel is first determined, followed by a comparison of the amount of bandwidth requested by, or required by a new subscriber. If the bandwidth available on a particular channel is adequate, service can be provided on the channel, otherwise the new subscriber is assigned to a new channel to avoid data overload.

A method and system are disclosed for enabling full-service communications between a full-service cable modem termination system (fsCMTS) and a plurality of full-service cable modems (fsCMs) for a conventional two-way hybrid fiber-coax (HFC) cable television network. Full-service communications include data, voice and video. Video includes broadcast quality MPEG-2 transport packet streams and Internet Protocol media streams. A multi-channel full-service media-access-control (fsMAC) coordinates the access to the shared upstream and downstream channels. Several MAC management messages are defined to enable a multi-channel full-service MAC domain to facilitate sharing of an arbitrary number of channels and to enable packet-by-packet true seamless channel change. Multiple upstream channels can be used in various ways to best optimize the use of the spectrum for meeting the quality-of-services needed by different services.

In a cable modem system, signals are transmitted upstream from a cable modem (CM) to a cable modem termination unit (CMTS) when the subscriber desires to communicate with the headend. The invention described herein is directed to a method and apparatus for increasing the communication channel between the CM and the CMTS. This is accomplished by providing a method and apparatus for increasing physical layer flexibility in cable modem systems. In this manner, the CMTS is capable of assigning burst profiles and granting mini-slots to the CMs according to the CMs' burst profile and robustness level.

Methods for reducing interference from initializing network devices in a data-over-cable system. The method includes aligning Initial Maintenance intervals for multiple upstream channels of the data-over-cable system. A cable modem termination system determines if usage intervals for the upstream channels may accommodate Initial Maintenance intervals that start at a common time. If so, the cable modem termination system constructs Bandwidth Allocation MAP messages for the usage intervals that contain Initial Maintenance intervals timed to start at the common time. In response to the MAP messages, initializing network devices range when there are no scheduled data transmissions on any upstream channel. The method may shorten a cable modem's time for ranging and may decrease collisions with data transmissions on the upstream paths when cable modems try to initialize.

A frequency agile cable modem termination system which is configured to receive cable TV or other broadband signals on a frequency allocated basis. Cable TV headend may receive cable TV modem or other signals via optical / electrical converters and other links, and route those signals through a frequency multiplexer to divide individual feeds into separated frequency slots. The cable modem termination system may then have receivers tuned to individual slots allocated to data feeds, such as Internet, video, telephony or other sources, and route those sources over the Internet. Upon a failure condition within any given receiver or other component, a backup cable modem termination system, connected to the same common bus as the main or active system, may be rapidly activated by having backup receivers contained in that unit tuned to appropriate frequencies to pick up the signals within the corresponding band. Reliability and robustness is increased, and cabling requirements are decreased.

A mutual authentication method in a Downloadable Conditional Access System (DCAS) is provided. The mutual authentication method may receive authentication-related information about authentication between an authentication unit and a security module (SM) from a Trusted Authority (TA), generate an authentication session key using the authentication-related information, transmit the authentication session key by the authentication unit to the SM through a Cable Modem Termination System (CMTS), and control a Conditional Access System (CAS) software to be downloaded to the SM from the authentication unit, when the authentication is completed by the authentication session key.

A cable modem communication system includes a plurality of Cable Modems (CMs), a CM network segment, and a Cable Modem Termination System (CMTS). The CMTS segregates the plurality of CMs into a first group of CMs with which standard registering and ranging operations are performed and a second group of CMs with which attenuated transmission registering and ranging operations are performed. Each CM of the first group of CMs operable to perform registering and ranging operations by transmitting a ranging burst of a first format. Each CM of the second group of CMs operable to perform registering and ranging operations by transmitting a ranging burst of a second format that differs from the ranging burst of the first format. The CMTS may include a rake receiver that receives and demodulates a plurality of multi-path copies of the ranging burst of the second format.

An apparatus may include a receiver configured to receive chunks of data on a downstream channel from a cable modem termination system. The receiver may be further configured to enter a low power state in which the chunks of data cannot be received. Wake up circuitry may be configured to monitor data in the downstream channel for a wake up signal when the receiver is in the low power state.

A method and system are disclosed for enabling full-service communications between a full-service cable modem termination system (fsCMTS) and a plurality of full-service cable modems (fsCMs) for a conventional two way hybrid fiber-coax (HFC) cable television network. Full-service communications include data, voice and video. Video includes broadcast quality MPEG-2 transport packet streams and Internet protocol media streams. A multi-channel full-service media-access-control (fsMAC) coordinates the access to the shared upstream and downstream channels. Several MAC management messages are defined to enable a multi-channel full-service MAC domain to facilitate sharing of an arbitrary number of channels and to enable packet-by-packet true seamless channel change. Multiple upstream channels can be used in various ways to best optimize the use of the spectrum for meeting the quality-of-services needed by different services.

A transmitter for use in a cable modem termination system includes a data processing module that generates a plurality of OFDM symbols from a data packet. A probe symbol generator generates a probe symbol, as one of a plurality of probe symbol types. The probe symbol is selectively inserted within the plurality of OFDM symbols, at a pre-defined probe symbol interval.

Distributed CMTS device for a HFC CATV network serving multiple neighborhoods by multiple individual cables, in which the QAM modulators that provide data for the individual cables are divided between QAM modulators located at the cable plant, and remote QAM modulators ideally located at the fiber nodes. A basic set of CATV QAM data waveforms may be transmitted to the nodes using a first fiber, and a second set of IP / on-demand data may be transmitted to the nodes using an alternate fiber or alternate fiber frequency, and optionally other protocols such as Ethernet protocols. The nodes will extract the data specific to each neighborhood and inject this data into unused QAM channels, thus achieving improved data transmission rates through finer granularity. A computerized “virtual shelf” control system for this system is also disclosed. The system has high backward compatibility, and can be configured to mimic a conventional cable plant CMTS.

Methods, apparatus, and computer-readable media are disclosed for performing diagnostic tests of a communication link between a headend and a cable modem without having to assign an IP address to the cable modem. The diagnostic tests are performed at the MAC layer and test the state of the hardware between and including the cable modem termination system (CMTS) and a selected cable modem. By doing so, a network operator is able to more easily focus in on a potential problem in cable RF / MAC connectivity between the two components by first eliminating (or identifying) a problem with hardware before focusing on problem-solving at the software level, typically at the Network layer, at which point the cable modem is assigned an IP address.