3com Corporation

U.S. Robotics Corporation

Utstarcom, Incorporated

U.S. Robotics Access Corp.

Dale M Walsh

Andrew L Norrell

Robert C Suffern

Christopher R Hansen

Donald C Balton

Marc S Baum

Terrel L Jones

Thanh Q Ngo

Vladimir G Parizhsky

Daniel L Schoo

Gregory Warren Goodknight

Don Bellenger

Jeffrey E Herman

Richard G C Williams

John R Rosenlof

William Kurt Dobson

Clifford H Wallach

Vitali Vinokour

Jeffery E Herman

A local area network connected to an infrastructure access device that provides the home LAN with access to voice, data and television services. The infrastructure access device includes a gateway to voice over Internet Protocol services, an interface to a data network for data access, a router to multiplex signals from the gateways and the data network and a Digital Subscriber Line (DSL) transceiver connected to a gateway device in the customer premises. The gateway device includes a DSL transceiver to communicate over the DSL connecting it to the infrastructure access device to provide the home LAN with high performance communications services without the use of POTS. The DSL transceiver may communicate using a switched carrier modulation scheme to conserve power and reduce crosstalk.

Converged home gateway

The subject invention defines the details of packet based DSL modulation. The invention claims a method for minimizing crosstalk generation by specifying a duty cycle for bursted carrier data traffic and a method of providing opportunistic echo canceller training. In this way the present invention minimizes power and interference while maximizing the peak capacity of a transceiver used in ADSL communication systems.

Packet modulation for DSL

Apparatus and method for enabling bilateral transmission of digital data between a local area network and telephone company networks employing both analog and digital telephone lines. A modem modulates signals responsive to signals from a local area network representing an outgoing call to form digital telephone signals suitable for transmission by a telephone line and suitable for demodulation by receiving analog modems. A circuit switched time division multiplex bus transmits the digital telephone signals to the telephone line. The modem also demodulates incoming digital telephone signals to form digital network bus signals divided into packets. A packet bus transmits the digital network bus signals to a network interface which processes the signals and transmits them to the local area network.

Network access method and network access server therefor

A method and apparatus for determining the correct decision regions in a PCM communication receiver utilizing a public Digital Telephone Network (DTN). A receiver receives samples from an analog loop of the DTN and quantizes the samples according to a reference lattice. The reference lattice defines a set of decision levels representing the quantization level for each PCM codeword. The receiver sets the reference lattice by scaling the lattice to account for the characteristics of the communication channel, which typically includes distortions of the digital data resulting in nonlinear behavior of the channel. The scaling and re-scaling thus accounts for PCM codeword translations or other channel distortion.

Method and apparatus for determining PCM code translations

An apparatus and method for adaptively equalizing a signal received from a remote transmitter. The equalizer includes a filter having an output and a decision circuit coupled to the filter output. In addition, the equalizer has a reference coupled to the decision circuit. The reference includes a model of a non-linear characteristic of a remote transmitter. The method relates to adaptively equalizing a signal received from a remote transmitter. The method includes the step of receiving a signal corresponding to a predetermined reference level from the remote transmitter. Next, the received signal level is filtered to remove linear error terms. The next step of the method includes measuring a non-linear error term associated with the received and filtered signal. The measured non-linear error term may then be stored and used to make improved decisions on data signals transmitted from the remote transmitter.

Method and apparatus for adaptively equalizing a signal received from a

A method for identifying that a data communications device is operable in a predetermined mode. The first step of the method provides for generating a frequency division modulation capabilities signal. The generated signal is limited to a predetermined frequency range. The method further provides for superimposing mode identification information upon the generated signal to form a modified signal. Like the generated signal, the modified signal falls within the predetermined range. The superimposed mode identification information may be applied by frequency modulating the generated signal.

Mode signalling method and apparatus

Digital network access server

Modem input/output signal processing techniques

Techniques for generating a line probing signal. The probing signal is comprised of a plurality of different tones, where the tones have a predetermined phase relationship. The signal may be sent over a communication channel, such as a telephone line. By so using the line probing signal, the non-linearity of the electrical characteristics of the telephone line may be measured with increased accuracy.

Modem line probing signal techniques

A modem for connecting data terminal equipment (DTE) to a remote DTE via a general switched telephone network or leased lines at data rates of 300, 1200 and 2400 bps using standard modulation techniques, and additonally providing virtual full duplex transmission capability at 9600 bps using trellis code modulation (TCM). The high-speed 9600 bps path is implemented by asymmetrical frequency division of the available bandwidth into a high speed, wideband forward channel (9600 bps) and a low speed, narrowband backchannel (300 bps). The high speed transmitting channel is assigned to that modem having the greatest data demand and the direction is dynamically reversed whenever the amount of data awaiting transmission over the low speed channel exceeds a predetermined maximum backlog, provided that a direction reversal has not taken place for at least a specified minimum interval during which use of the forward channel is guaranteed. To improve the efficiency of the backchannel, extended data formats are added to the MNP link protocol for use in backchannel transmission and to control direction reversals on the line. The modem is implemented with three available general purpose microprocessors with interprocessor communications being synchronized by a timer driven interrupt mechanism. A hardware timer/counter built into one of these processors is used to monitor the signals on the telephone line to detect and distinguish answer tones, voice signals, busy signals, ringback signals and dial tones. A hardware counter/timer is also used to measure the width of the start bit from the serial port to form the basis for a calculation of the baud rate being used by the DTE.

Asymmetrical duplex error-controlled modem

Growing community of inventors

Golf, IL, United States of America

Dale M Walsh