Lucent Technologies Inc.

Bell Telephone Laboratories

American Telephone and Telegraph, Co.

American Telephone & Telegraph Co., At&t Bell Laboratories

Curtis A Siller

Subrahmanyam Dravida

Peter David Magill

Bharat Tarachand Doshi

Kotikalapudi Sriram

George John Kustka

Walter Debus, Jr

Howard C Reeve, Iii

Vijay K Bhagavath

Thomas L Osborne

The specification relates to a method and apparatus supporting multiple access, bi-directional data and multimedia transfer described over a hybrid fiber/coax (HFC) network, though applicable to transmissions over other media as well. The protocol associated with the present invention supports downstream broadcast transmission from headend to cable modem, and also provides for allocation of bandwidth for cable modems to transmit back to the headend. The protocol supports different access modes such as STM, ATM, and VL; within each subframe of a subframe/frame/masterframe structure. The protocol is utilized over a system which provides for forward error correction (FEC) and scrambling/descrambling, while eliminating the deleterious effects on the error correcting capability of the FEC due to the bit error spreading associated with a scrambling/descrambling function. The protocol adapts to changing demands for a mix of circuit and packet mode applications and allocates upstream and downstream bandwidth in response to the a variety of bursty and isochronous traffic sources.

Method and apparatus for digital transmission incorporating scrambling and forward error correction while preventing bit error spreading associated with descrambling

The specification relates to a broadband multiple access protocol for bi-directional hybrid fiber/coax (HFC) networks. The protocol supports downstream broadcast transmission from headend to cable modem, and also provides for allocation of bandwidth for cable modems to transmit back to the headend. Although the present invention is described in relation to an HFC network, it is also equally applicable to a wireless communications environment. The protocol supports different access modes such as synchronous transfer mode, asynchronous transfer mode, and variable length data. The protocol adapts to changing demands for a mix of circuit and packet mode applications and allocates upstream and downstream bandwidth in response to the a variety of bursty and isochronous traffic sources. In order to satisfy the quality of service requirements of varied applications, while maintaining high bandwidth efficiency, the protocol utilizes a frame structure with frame partitioning into regions; one region dedicated to STM payload and asynchronous, second region dedicated to ATM and VL payloads, messaging and control.

Method and apparatus enabling synchronous transfer mode, variable length

The specification relates to a broadband multiple access protocol for bi-directional hybrid fiber/coax (HFC) networks. The protocol supports downstream broadcast transmission from headend to cable modem, and also provides for allocation of bandwidth for cable modems to transmit back to the headend. Although the present invention is described in relation to an HFC network, it is also equally applicable to a cellular wireless communications environment. The protocol supports different access modes such as STM, ATM, and VL; within each subframe of a subframe/frame/masterframe structure. The protocol adapts to changing demands for a mix of circuit and packet mode applications and allocates upstream and downstream bandwidth in response to the a variety of bursty and isochronous traffic sources. In order to satisfy the quality of service requirements of varied applications, while maintaining high bandwidth efficiency, the protocol utilizes a subframe structure with subframe partitioning into regions; one region dedicated to STM payload transmission, a second region dedicated to ATM cell transmission, and a third region dedicated to VL payload transmissions.

Method and apparatus enabling multiple access for multiple services and

A unique simple and generic ABR-MAC interoperability approach is employed which minimizes the impact of a Host Digital Terminal (HDT) ATM switch ABR connection on individual Information Appliances (IAs present at customer premises) and by employing a suitable MAC protocol to transfer data to an ATM network interface buffer (ATM-NI) located at the HDT. To this end, a unique arrangement is employed to regulate the buffer storage unit status in an ATM-NI. More specifically, the arrangement monitors upstream data traffic from active IA-HDT connections and, additionally, any incipient IA-HDT connections. This is realized by employing dual ATM-NI buffer storage unit threshold values that are selected depending on a particular ATM-NI buffer storage providing the particular information appliance on an active connection with information to allow the information appliance to adjust its transmission unit capacity, namely, a low, i.e., first, threshold value and a high, i.e., second, threshold value. In a particular embodiment, a predetermined parameter (k) is defined to specify a number of frames that have elapsed before a next upstream ATM cell is to be transmitted to the ATM-NI buffer storage unit at the HDT. If the amount of data stored in the ATM-NI buffer storage unit is less than the low threshold value, this implies a normal 'uncongested' state of operation of the ATM-NI buffer storage unit. If the amount of data in the ATM-NI buffer storage unit is greater than the low threshold value but less than the high threshold value, regulation of the rate of data being supplied to the ATM-NI buffer storage unit must be performed. If the amount of data stored in the ATM-NI buffer storage unit is greater than the high threshold value, transmission of additional data to it is not allowed.

Asynchronous transfer mode and media access protocol interoperability

A technique is presented for simplifying the recovery of two synchronous data signals having a common symbol rate after each signal has respectively modulated a different one of a pair of quadrature-related carrier signals. In the transmitter, the data signal which modulates one of the quadrature-related carrier signals is delayed relative to the data signal which modulates the other quadrature-related carrier signal. This delay is related to an IF frequency chosen at the receiver. After passing through a noisy transmission channel, the quadrature-related carrier signals are coupled in the receiver to a serial combination of an equalizer and analog-to-digital converter. This combination outputs multiple, substantially distortion-free samples of the data signals each symbol interval. The two data signals are then recovered by selecting a subset of the samples provided each symbol interval.

Simplified recovery of data signals from quadrature-related carrier

A technique for digitally synthesizing the amplitude modulation of one or more carrier signals with a random digital data signal is disclosed. Pursuant to the present invention, a memory unit is addressed by a plurality of binary coded digital symbols in the data signal. For each address, at least two digital representations are read out. Each representation corresponds to a different sample of the carrier signals which has been amplitude modulated by a composite of the spectrally shaped data signal. The disclosed technique can be adapted to synthesize a variety of modulation formats, and can provide compensation for fixed in-rail and cross-rail distortions.

Technique for synthesizing the modulation of a time varying waveform

A digital synthesis technique provides pulse shaping in accordance with predetermined time domain and frequency domain constraints. In the technique, the informational content of a binary bit stream is used by an access circuit (12) to form address words for accessing a read-only-memory (13). The digital representations stored in the ROM (13) represent a superposition of temporally-displaced truncated impulse time functions, each weighted by the discrete transmission symbol levels of the analog output signal. The digital representations from two ROMs (13-1 and 13-2) are toggled by a sequencng circuit. In other embodiments of the invention, different memory arrangements ranging from a signal ROM (142) to an array of ROMS (163-1 through 163-3 and 164-1 through 164-3) are respectively used to decrease circuit complexity. In a digital radio transmission application of the technique, this arrangement is economical, readily reproducible and stable since it obviates the need for conventional complex analog filters.

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Andover, MA, United States of America

Curtis A Siller