Abstract: A balanced hybrid circuit for compensating for transmission echo signal in a modem. The hybrid circuit includes transmission echo compensation circuits that approximate the echo signal effects of the line and line transformer, respectively, and produce a transmission echo signal replica. A sample of the transmission signal and the replica of the transmission echo are then subtracted from the signal received on the line to produce a received signal isolated from the transmission signal and the transmission echo signal.

Abstract: Network access apparatus includes a slave unit, including a plurality of subscriber ports adapted to be linked to respective subscriber lines, and a multiplexer for multiplexing among the ports. A master sub-system, is connected to at least one trunk line of a first public network, in a location remote from the slave unit. The master sub-system includes a first master unit, adapted to communicate with the slave unit via an assigned link through a second public network, so as to provide users of the subscriber lines with access to the first public network through the at least one trunk line. The master sub-system also includes a second master unit, coupled through the first master unit to communicate with the slave unit via the assigned link, so as to provide the users with access to the first public network through the at least one trunk line in the event of a failure associated with the first master unit.

Abstract: Communication access apparatus includes a master shelf, including a master switching unit linked to communicate with a high-speed network, and a plurality of slave shelves arranged in a given system topology with respect to the master shelf. Each of the slave shelves includes ports configured to serve network subscribers, and further includes a slave switching unit, coupled to communicate with the master switching unit and to multiplex among the ports so as to provide the subscribers with access to the high-speed network, and to receive from the master shelf management messages that are addressed to an internal network-layer address that is determined uniquely for each of the slave shelves based on the topology.

Abstract: Communication access apparatus includes a master shelf, including a master switching unit linked to communicate with a high-speed network, and a plurality of slave shelves. Each slave shelf includes ports that serve network subscribers, and further includes a slave switching unit, coupled to communicate with the master switching unit and to multiplex among the ports so as to provide the subscribers with access to the high-speed network. A management station is coupled to communicate with the master shelf and the plurality of slave shelves over a management network in which all of the slave shelves are on a single subnet.

Abstract: A method for controlling data transmission over a network includes receiving a succession of data packets from a packet input at a potentially variable input rate, each packet in the succession potentially having a respective, non-uniform packet size. For each of the packets in the succession, the respective packet size is compared to a transmission credit allocated to the input. If the allocated credit is sufficient, compared to the respective packet size, the packet is transmitted over the network at a peak transmission rate predetermined by the network. If the allocated credit is insufficient, compared to the respective size, at least a portion of the packet is transmitted over the network at a rate no greater than a sustainable transmission rate predetermined by the network, which sustainable transmission rate is less than the peak transmission rate.

Abstract: A digital data receiver, for receiving a signal that is transmitted over a channel having a channel response and is filtered with a predetermined filter response. The receiver includes a decision device, coupled to receive a sequence of equalized samples and to generate, responsive thereto, a corresponding sequence of estimated symbols. A feed-forward equalizer receives a sequence of input samples of the signal and generates responsive to the input samples, forward-equalized samples. A decision feedback equalizer (DFE), which receives the sequence of estimated symbols, includes an adaptive element, which processes the estimated symbols responsive to the channel response, and a fixed element, which processes the estimated symbols responsive to the predetermined filter response. The DFE generates feedback-equalized samples by combined operation of the adaptive and fixed elements.

Abstract: Multiplexing apparatus for providing access to a high-speed network over a plurality of subscriber lines. One or more line cards include ports to the subscriber lines, at least one of the line cards including a volatile memory for storing backup configuration parameters of the apparatus. A switching unit includes a non-volatile memory, adapted to store operating configuration parameters. A controller in the switching unit is operative to receive the backup configuration parameters stored in the volatile memory and to update the operating configuration parameters in the non-volatile memory responsive to the backup configuration parameters. The switching unit also includes a communication interface, over which it is coupled to communicate with the network in accordance with the operating configuration parameters so as to link the ports of the line cards to the network.

Abstract: A bandwidth sharing method for use on respective interstitial connections between on one side a plurality of users and on the other side a common data-link having a shared packet switching device, the method including performing the steps of: monitoring data-link directed bandwidth from each user; maintaining a current sum of the monitored bandwidth; and whenever the current sum exceeds a predetermined data-link bandwidth threshold, reducing current collective data-link directed bandwidth by for substantially each user, comparing the respective user's data-link directed bandwidth with a predetermined data-link bandwidth threshold for the respective user; using an allocation function, selecting at least one user who is exceeding his predetermined data-link bandwidth threshold, and for a predetermined time interval, cutting the connection between each selected at least one user and the shared switching device, so as to restore a current sum of the monitored bandwidth to be not greater than the predet

Abstract: Network access apparatus includes first and second master units, each having a physical interface to a packet-switched network. A plurality of slave units, each slave unit having one or more ports to respective subscriber lines, are linked by a plurality of physical interface lines in one or more daisy chains, in which the slave units are mutually connected in series by the physical interface lines therebetween. Each daisy chain includes at least a first slave unit connected by one of the physical interface lines to the first master unit and a last slave unit connected by another of the physical interface lines to the second master unit.

Abstract: A method for communicating at least one of the hook state and associated in line filter indication from the ADSL Transceiver Unit-Remote Side to the ADSL Transceiver Unit-Central Office, or vice versa, for improving the performance of splitterless ADSL systems. This information is used to determine robust bits and gain allocation during startup, and to correct the profile selection during fast retrain.

Abstract: A splitterless system provides along a subscriber loop, full Ethernet wire speed data transmission between a date source and an Ethernet standard end device. The system includes a gateway modem device connected to a data source, and arranged in splitterless contact with a subscriber loop extending between a Punch Down Block (PDB), and an Ethernet standard end device; and a user modem device connected between the Ethernet standard end device and the subscriber loop so as to define with the gateway modem device a subscriber loop segment, wherein the gateway modem device and the user modem device are operative to communicate along the loop segment in different predetermined, first and second frequency spectra, for uplinking and downlinking, respectively, thus to facilitate therealong full Ethernet wire speed data transmission therealong.

Abstract: In a communication network that includes a plurality of nodes interconnected by links, a method for routing a data flow includes receiving a request to allocate one or more resources in the network so as to carry the data flow between first and second ones of the nodes over one of a plurality of paths therebetween, each such path including a respective sequence of the links. For the links included in each of the paths, respective levels of use of the requested resources due to communications in process over the network are determined. The path that is to carry the data flow is selected responsive to the determined levels of use of the requested resources on the links included in each of the paths.

Abstract: A method for managing a buffer includes receiving a stream of data fragments into the buffer, at least some of the fragments being arranged in packets, each such packet comprising a last fragment. While a fill level of the buffer remains below a first threshold, the received fragments are accepted into the buffer. When the fill level of the buffer increases above the first threshold, the buffer continues to accept the received fragments until the last fragment in one of the packets is received or until the fill level of the buffer increases above a second threshold, greater than the first threshold. When the last fragment in one of the packets is received, the fragments that are received thereafter are discarded until the last fragment in another, subsequent one of the packets is received and the fill level of the buffer is no longer above the first threshold. The buffer then continues to accept the received fragments.

Abstract: A method and apparatus for transmitting data over a channel having a variable transmission rate. A transmitter determines the rate of transmission of the data over the channel and receives a datagram for transmission over the channel at the determined rate of transmission. The transmitter divides the datagram into fragments of a size no greater than a size limit that is set for the datagram responsive to the determined rate of transmission and transmits the fragments over the channel.

Abstract: A method for routing a data flow from a source node to a destination node among a plurality of nodes mutually linked in a ring by segments of a communication network, configured so that the data flow can traverse the ring in either of first and second, mutually-opposing directions of communication. The method includes maintaining at each of the nodes a record of respective levels of use of a network resource on the segments in the ring for both the first and second directions of communication. Responsive to the respective levels of use, one of the directions is selected at the source node, in which to route the data flow to the destination node. A notification is sent from the source node to the other nodes in the ring of an additional allocation of the resource required by the source node in order to convey the data flow to the destination node in the selected direction on the segments in the ring.

Abstract: This invention discloses an apparatus for transmission of high speed data over communication channels, the apparatus including a modulator operative to modulate an outgoing stream of digital data, thereby to generate an outgoing signal, and a demodulator operative to demodulate an incoming signal, thereby to generate an incoming stream of digital data, wherein the modulator comprises a band suppressor for suppressing portions of the outgoing signal which have specified frequencies.

Abstract: A line driver for coupling a data transceiver to a line having a load impedance, having a transformer with a primary coil and a secondary coil with a turns ratio of N:1 therebetween. The line driver includes a shunt impedance set to a value equal to a predetermined function of N and of the load impedance, coupled between one end of the primary coil and ground. The line driver also includes a differential amplifier, having a first input coupled to be driven by a transmit circuit of the transceiver, and having an output coupled to drive the line through the secondary of the transformer, and having a second input shunted to ground through the shunt impedance and coupled to receive feedback from the output through the primary coil of the transformer.

Abstract: A method for reducing probability of clipping in an IFFT-based (inverse fast Fourier transform based) multitone communication transmitter, the method including applying an IFFT to an original sequence thereby to generate an IFFT output sequence, if the IFFT output sequence fits a predetermined clipping profile, applying at least one transformation to the IFFT output sequence, thereby to define a transmitted sequence, the transformation-applying step including decomposing the IFFT output sequence into a first component sequence and a second component sequence, rearranging at least one of the first and second component sequences with respect to the other, thereby to define third and fourth component sequences, and combining the third and fourth component sequences into a final output sequence.

Abstract: This invention discloses an apparatus for transmission of high speed data over communication channels, the apparatus including a modulator operative to modulate an outgoing stream of digital data, thereby to generate an outgoing signal, and a demodulator operative to demodulate an incoming signal, thereby to generate an incoming stream of digital data, wherein the modulator comprises a band suppressor for suppressing portions of the outgoing signal which have specified frequencies.

Abstract: An interleaver which allows the use of consecutive groups of codewords within a frame, where the maximum size of each codeword is constrained to be equal to or less than a certain maximum size. In accordance with required performance standards, i.e., the specification of a maximum number of data errors that the system is supposed to withstand, the interleaver is capable of limiting the number of errors which occur within a specific codeword to be less than the maximum number of errors that can be corrected by the particular coding scheme. The interleaver is able to achieve this result even for codewords of uneven length. The interleaver attempts to divide the total number of symbols to be transmitted in a frame into equal size codewords. If the codeword size cannot be made equal, then unequal size codewords are used, however, the difference in size between codewords cannot be greater than one symbol.