Consistent with a further aspect of the present disclosure, previously encoded data is stored in a memory, and an encoder accesses both input data and previously encoded data to generate new encoded data or a new codeword. Each codeword is stored in a row of the memory, and with each newly generated codeword, each previously stored code word is shifted to an adjacent row of the memory. In one example, the memory is delineated as a plurality of blocks including rows and columns of bits. When generating a new code word, randomly selected columns of bits in the memory are read from randomly selected blocks of the memory and supplied to the encoder. In this manner the number of times the memory is access is reduced and power consumption is reduced.
H03M 13/15 - Cyclic codes, i.e. cyclic shifts of codewords produce other codewords, e.g. codes defined by a generator polynomial, Bose-Chaudhuri-Hocquenghem [BCH] codes
H03M 13/27 - Coding, decoding or code conversion, for error detection or error correctionCoding theory basic assumptionsCoding boundsError probability evaluation methodsChannel modelsSimulation or testing of codes using interleaving techniques
H03M 13/29 - Coding, decoding or code conversion, for error detection or error correctionCoding theory basic assumptionsCoding boundsError probability evaluation methodsChannel modelsSimulation or testing of codes combining two or more codes or code structures, e.g. product codes, generalised product codes, concatenated codes, inner and outer codes
2.
OPTICAL SUBCARRIER DUAL-PATH PROTECTION AND RESTORATION FOR OPTICAL COMMUNICATIONS NETWORKS
An example system includes a first network device having first circuitry. The first network device is configured to perform operations including receiving data to be transmitted to a second network device over an optical communications network, and transmitting first information and second information to the second device. The first information is indicative of the data, and is transmitted using a first communications link of the optical communications network and using a first subset of optical subcarriers. The second information is indicative of the data, and is transmitted using a second communications link of the optical communications network and using a second subset of optical subcarriers. The first subset of optical subcarriers is different from the second subset of optical subcarriers.
Optical subcarriers may be employed to transmit data in a point-to-multi-point network whereby a hub node including a network switch receives such data from a client and transmits information indicative of such data to multiple leaf or network nodes, where data intended for such leaf node is output. Often the rate at which data is supplied to the hub node is different than the rate at which information indicative of the data is transmitted. Moreover, the client data may have a format that is different than that associated with the transmitted information indicative of the client data. Consistent with the present disclosure, client data is inverse multiplexed to lower data rate streams and then multiplexed to a plurality of inputs, each of which corresponding to a respective optical subcarrier. Information indicative of the data may be allocated to multiple subcarriers, if the a single carrier lacks sufficient capacity or bandwidth to meet the bandwidth requirements of the leaf node. Buffer circuits may also be employed to "shape" or delay the outputs or flows of the multiplexer so that data is fed, for example, to a transmit portion of chip 200b of the network switch at a uniform rate rather than in non-uniform data bursts, which, under certain circumstances, could exceed the capacity of such transmit portion. In a further example, leaf nodes include circuitry for monitoring the amount of received data, and, if such received exceeds a certain threshold, a request is sent from the leaf node to the hub to transmit data at a rate equal to or substantially equal to the received data rate. As a result, symmetric data flows may be achieved whereby the leaf nodes transmit and receive data at the same or substantially the same rate.
An optical transceiver with a built-in heat transfer structure is described. The heat transfer structure can connect one or more circuit regions of the optical transceiver to a heat sink while bypassing circuit regions that may impede the transfer of heat from the one or more circuit regions. The heat transfer structure may directly contact the one or more circuit regions, and the heat sink and may include an opening to avoid contact with the circuit regions to be bypassed.
An optical transceiver having a locking assembly that prevents undesirable movement of the optical transceiver when engaged with another device is described. The locking assembly includes a slide with a projection, lift, and weighted stops. In a first configuration, the slide and weighted stops can sustain contact between a thermal interface material of the optical transceiver and the other device while locking the optical transceiver to prevent movement. In a second configuraton mode, the locking assembly disengages the thermal interface material from the other device and unlocks the weighted stops to permit disconnection from the other device.
An example node includes a receiver, a switch circuit, and a transmitter. The receiver is configured to receive a first modulated optical signal including a first plurality of optical subcarriers, and supply a plurality of data streams based on the first plurality of optical subcarriers. Each of the data streams is associated with a corresponding one of the plurality of optical subcarriers. The switch circuit is configured to receive the data streams, and supply the data streams to a plurality of switch outputs. The transmitter is configured to receive the data streams, and supply a second modulated optical signal based on the data streams. The second modulated optical signal carries a second plurality of optical subcarriers. Each of the second plurality of optical subcarriers is associated with a corresponding one of the data streams.
An example system includes a hub transceiver and a plurality of edge transceivers. The hub transceiver is operable to transmit, over a first communications channel, a first message to each of the edge transceivers concurrently, including an indication of available network resources on an optical communications network. Each of the edge transceiver is operable to transmit, transmit, over a second communications channel, a respective second message to the hub transceiver including an indication of a respective subset of the available network resources selected by the edge transceiver for use in communicating over the optical communications network. Further, the edge transceiver is operable to receive, from the hub transceiver, a third message acknowledging receipt of a selection and a fourth message confirming an assignment of the selected subset of the available network resources to the edge transceiver.
H04B 10/00 - Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
Techniques are described for implementing an out-of-band communication channel used to exchange control channel information in sub-carrier-based optical communication systems. In an example implementation, a transmitter includes a laser operable to supply an optical signal, a digital signal processor operable to supply first electrical signals based on first data input to the digital signal processor and second data input to the digital signal processor, digital-to-analog conversion circuitry operable to output second electrical signals based on the first electrical signals, modulator driver circuitry is operable to output third electrical signals based on the second electrical signals, and an optical modulator operable to supply first and second modulated optical signals based on the third electrical signals. The first modulated optical signal includes a plurality of optical subcarriers carrying user data. The second modulated optical signal is polarization modulated based on the second data.
H04B 10/00 - Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
This disclosure describes digitally generating sub-carriers (SCs) to provide isolation and dynamic allocation of bandwidth between uplink and downlink traffic between transceivers that are communicatively coupled via a bidirectional link including one or more segments of optical fiber. Separate uplink and downlink communication channels may be created using digitally generated SCs and using the same transmitter laser. In some implementations, one or more of the nodes include a transceiver having at least one laser and one digital signal processing (DSP) operable for digitally generating at least two SCs and detecting at least two SCs. The transceiver can transmit selected SCs, and can receive other SCs. Accordingly, the transceiver can facilitate bidirectional communication, for example, over a single optical fiber link. In some instances, techniques can facilitate dynamic bandwidth assignment by facilitating adding or blocking of optical subcarriers from transmission in an uplink or downlink direction.
H04B 10/00 - Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
Methods, systems, and apparatus, including computer programs encoded on computer storage media, for clock synchronizing an optical system and multiple leaf systems. In some implementations, an apparatus includes a receiver comprising: a local oscillator laser providing a local oscillator signal, a detector circuit operable to receive a first optical signal and detect first data carried by the first optical signal based on the local oscillator signal, a reference clock circuit supplying a clock signal, a digital signal processor (DSP) operable to receive the first data and supply a control signal to the reference clock circuit based on the first data, the reference clock circuit being operable to adjust the clock signal based on the control signal; and a transmitter operable to output a second optical signal carrying second data, the second data having an associated rate that is based on the clock signal.
H04B 10/00 - Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
A transmitter can include a laser operable to output an optical signal; a digital signal processor operable to receive data and provide a plurality of electrical signals based on the data; and a modulator operable to modulate the optical signal to provide a plurality of optical subcarriers based on the plurality of electrical signals. One of the plurality of subcarriers carries first information indicative of a first portion of the data in a first time slot and second information indicative of a second portion of the data in a second time slot. The first information is associated with a first node remote from the transmitter and the second information is associated with a second node remote from the transmitter. Receivers as well as systems also are described.
A network or system in which a hub or primary node may communicate with a plurality of leaf or secondary nodes. The hub node may operate or have a capacity greater than that of the leaf nodes. Accordingly, relatively inexpensive leaf nodes may be deployed to receive data carrying optical signals from, and supply data carrying optical signals to, the hub node. One or more connections may couple each leaf node to the hub node, whereby each connection may include one or more spans or segments of optical fibers, optical amplifiers, optical splitters/combiners, and optical add/drop multiplexer, for example. Optical subcarriers may be transmitted over such connections, each carrying a data stream. As the bandwidth or capacity requirements of the leaf nodes change, the number of subcarriers, and thus the amount of data provided to each node, may be changed accordingly.
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