At+t Corp.

Lucent Technologies Inc.

Other

James E Dail

Peter David Magill

Chia-Chang Li

Kotikalapudi Sriram

Roy S Coutinho

Miguel Dajer

Norman A Whitaker, Jr

Robert Alan Pitsch

Hayder Sadiq Radha

Hamid Reza Rabiee

The compression of composite video data is provided in order to reduce bandwidth and thereby increase the amount of bandwidth available for transmission. Composite video signals that include a plurality of fields are received at a selected clock frequency. A first selected number of fields is stored and a second selected number of fields is dropped. In a Frequency Division Multiplexing mode, the data is read out at a fraction of the selected clock frequency corresponding to the stored portion. In a Time Division Multiplexing mode, the data is read out at the selected clock frequency during selected intervals having a duration corresponding to the time it took to receive the stored fields. No data is read out during an interval having a duration equal to the time it took to scan the dropped fields, such time being allocated to the compressed information from other users of the same shared transmission medium.

System and method for compressing video data for video conferencing at a

Increased upstream bandwidth and reduced ingress noise in a shared hybrid fiber-coax transmission system (100) are obtained by modulating at least a portion of upstream signals received from subscribers to a high frequency band (e.g., 750-1000 MHz), thereby increasing the upstream bandwidth. The high frequency upstream signals are then digitally regenerated in the coaxial cable (200) plant prior to receipt at a fiber node (180). At the fiber node, the high-frequency upstream signals are again digitally regenerated and are then transmitted optically in a baseband digital format between the fiber node (180) and a head end (120). The digital regeneration of the high frequency upstream signals, and the optical transmission of such signals in a baseband digital format reduces the incidence of ingress noise.

Hybrid fiber-coax system having at least one digital fiber node and

A head-end dynamically allocates bandwidth of a communications channel as a function of the type of communications traffic. In particular, the head-end communicates to subscriber stations via a broadband cable network using an access protocol, which is modified to provide a variable number of mini-slots and a variable number of data slots in each frame. Each mini-slot is used to request assignment of a data slot(s) to subscriber stations for the communication of information and, also, as a vehicle to resolve contention between subscriber stations. The head-end dynamically adjusts the number of mini-slots over a period time as a function of the type of communications traffic, e.g., bursty and isochronous traffic sources. Any variation in the number of mini-slots concomitantly effects the number of data slots available to communicate information. For example, less mini-slots provides more data slots. As a result, the dynamic adjustment of the number of mini-slots allows the head-end to more efficiently allocate bandwidth on the communications channel.

Method and apparatus enabling enhanced throughput efficiency by use of

A shared hybrid fiber-coax transmission system (100) includes at least one fiber node (180) that includes at least one receiver (460) for converting an upstream signal into a baseband digital format for conversion into a digitally modulated, optically-formatted signal for transmission to a head end (120). By converting the upstream signal into a digital baseband format for transmission in an optical format to the head end, ingress nose associated with the upstream signal can be reduced.

Hybrid fiber-coax system having at least one digital fiber node

Noise is reduced and bandwidth may be increased in a CATV transmission system by modulating a portion of subscriber-generated upstream signals to a high frequency band (e.g., 750-100 MHz) and then digitally regenerating such signals. To further reduce noise, the digitally regenerated upstream signals are transmitted by in a baseband digital format to the head end (120) via a digital E/O converter (330). Increased downstream bandwidth is obtained by modulating a portion of the downstream signals to a higher frequency band (e.g., 500-750 MHz) and then digitally regenerating such signals.

Ingress noise in a hybrid fiber-coax transmission system (10) may be reduced by employing asymmetric taps (30.sub.1 '-30.sub.8 ', 30.sub.1 '-30.sub.8 ',) between a pair of line extenders (28--28) for attenuating downstream and upstream information by different weights. The downstream weights of the taps are selected to achieve a substantial constant power level at each tap for individual subscribers (14--14). The upstream attenuation of each tap is selected to allow for a nearly constant level of subscriber-generated information to be received at the line extender while the subscriber generated upstream information is supplied to the taps at a constant value that is maximized to reduce the effect of ingress noise.

Method for asymmetrically attenuating signals in a transmission system

An apparatus and method for centralized processing of PIP images from a plurality of digital video sources includes a centralized processing device having a plurality of service drivers for outputting digital video data representing full screen images, and samplers for selectively sampling the data from the service drivers to form reduced screen images. A PIP bus channels the sampled data for access by various users. The sample data is selectively stored in buffers and is output to a display device when triggered by input/output triggers. The triggered output data representing reduced screen images is then combined by a video switch to form picture-in-picture images.

Device and method for centralized processing of picture-in-picture images

A hybrid fiber-coax network (100) includes at least one repeater (220.sub.1) dispersed within a coax trunk (22.sub.1) that carries video information downstream to a subscriber (14) and subscriber-originated information upstream to a fiber node (18). The repeater serves to digitally regenerate the subscriber-originated information to reduce ingress noise that would otherwise aggregate at the fiber node.

Shared hybrid fiber-coax network having reduced ingress noise in the

STM traffic, e.g. voice and video telephony (VT), as well as packet mode (e.g. ATM) traffic, e.g. broadcast digital video, interactive television, and data, are transmitted via a multiple access broadband fiber/coaxial cable network. Customer premises equipment (CPE) at stations, and a bandwidth controller, which may be at a head end or central office, with which all stations communicate, work together to adapt to the changing demands of the traffic mix, and efficiently allocate bandwidth to a variety of bursty and isochronous traffic sources. The bandwidth allocation defines two types of time slots, STM and ATM, and divides each frame into two corresponding STM and ATM regions. The boundary between the regions can be changed dynamically. A contention access signaling channel is provided in the STM region, for call control and set-up requests. Within the STM region, the time slots can be of variable length and be allocated on a per call basis; the length of the time slots is proportional to the bandwidth requirement of STM calls. Within the ATM region, the time slots are of fixed length, each capable of accommodating one ATM cell. Further, the fixed length ATM time slots may be reserved for a particular user for the duration of a call, or may be shared through a contention process. At least one contention ATM time slot is always made available for signaling messages related to ATM call control and set-up requests. The downstream time frame is structured in a similar manner, but includes an additional MAP field to transmit to the stations ATM time slot allocation and status information for time slots in the upstream channel.

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Marlboro, NJ, United States of America

James E Dail