Infinera Corporation

Prasad Paranjape

Ting-Kuang Chiang

Edward Everett Sprague

David F Welch

Drew Daniel Perkins

Parthiban Kandappan

Tulasi Veguru

Stephen G Grubb

Han Henry Sun

Steven Joseph Hand

Charles H Joyner

Biao Lu

Chung Kuang Chin

Mallikarjun Chillal

Tom Quoc Wellbaum

Yeongho Park

Michael D Jarchi

Konstantin Saunichev

Swaroop Raghunatha

Mats Plantare

Arvinderpal S Wander

Gopal Rao

Venkat Talapaneni

Steven G Grubb

Michael Kutty K G

Gus Elmer

Millikarjun Chillal

An example method is performed by a terrestrial control system communicatively coupled to a constellation of satellites. According to the method, instructions are transmitted to a first satellite of the constellation to transmit a plurality of first groups of optical subcarriers to a plurality of second satellites of the constellation via free-space optical communication. The first groups of optical subcarriers carry first data and each of the first groups of optical subcarriers is associated, respectively, with a different communications module of the second satellites. Further, instructions are transmitted to the second satellites to transmit a plurality of second optical subcarriers to the first satellite via free-space optical communication. The second groups of optical subcarriers carry second data and each of the second groups of optical subcarriers is associated, respectively, with a different communications module of the second satellites.

Transmitting and receiving data using a satellite communications network

An example apparatus includes an optical transmitter, an optical splitter, lenses, and mirrors. The optical splitter has an input and several outputs. The input of the optical splitter is optically coupled to the transmitter, such that each of the outputs of the optical splitter is operable to supply a corresponding one of a plurality of modulated optical signals, each of which includes a plurality of optical subcarriers. Each of the lenses is optically coupled to a respective one of the outputs of the optical splitter. Each of the lenses is operable to receive a corresponding one of the modulated optical signals. Each of the mirrors is optically coupled to a corresponding one of the lenses, such that each of the mirrors is operable to direct a respective one of the modulated optical signals for transmission through free space.

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 chipof 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.

Network switches systems for optical communications networks

An example apparatus includes a first communications module having a first transceiver. The first communications module is operable to transmit, using the first transceiver, a plurality of first groups of optical subcarriers to a plurality of second communications modules via free-space optical communication. The first groups of optical subcarriers carry first data, and each of the first groups of optical subcarriers is associated, respectively, with a different one of the second communications modules. The first communications module is also operable to receive, using the first transceiver, plurality of second groups of optical subcarriers from the second communications modules via free-space optical communication. The second groups of optical subcarriers carry second data and each of the second groups of optical subcarriers is associated, respectively, with a different one of the second communications modules.

Embodiments of the present invention analyze a plurality of parallel channels and identify specific channel(s) that have skew outside of an acceptable skew error margin. In certain embodiments, this skew is identified by determining the timing misalignment between a channel under test and a deskew channel. Other channels within the plurality of channels are masked by transmitting a repeating masked bit pattern. This timing misalignment may be measured by comparing a segment within the channel under test to a corresponding segment within the deskew channel and identifying a time differential between the two segments.

Channel skew identification and notification

A client receive circuit receives client data from a network, decodes the client data and stores the client data within the memory. A frame transmit circuit is provided that includes a justification control logic and a framer and a justification control logic is provided that 1) determines each of a plurality of fill levels and 2) determines an average of the plurality of fill levels. The framer has circuitry to generate a wrapper including a justification opportunity having data based upon a difference between the average and a predetermined threshold.

Methods and apparatus for minimizing wander generation in constant bit rate asynchronously mapped digital transport systems

Consistent the present disclosure, errored bits are inserted into a data stream, which is carried by an optical signal. The optical signal is transmitted over an optical link that may induce additional errors, i.e., add additional errored bits to the data stream. At the receive end, the optical signal is converted into a corresponding electrical signal that carries the data stream. The data stream is subject to forward error correction (FEC) decoding with an iterative decoder, for example. The iterative decoder decodes the data stream over a number of iterations until both the inserted errored bits and the additional errored bits are corrected. Since the number of inserted bits is known, the number of iterations required to correct the inserted bits is also known ('first iterations'). Accordingly, the number of iterations required to correct the additional errored bits caused by transmission over the optical link may be determined based on the total number of iterations performed and the number of the first iterations.

Apparatus and method for optimizing an iterative FEC decoder

Consistent with the present disclosure, client data, which may include multiplexed data sub-streams, is supplied to an ingress node of a network. Each sub-stream typically has a corresponding data rate, i.e., an original data rate, prior to multiplexing. The client data is encapsulated in a plurality of successive frames that are output from the ingress node and propagate, typically through one or more intermediate nodes, to an egress node. At the egress node, data rates associated with the sub-streams included in each frame are determined based on the amount of client data in each frame. The data rates are then averaged over a given number of frames to thereby filter any wander or deviation in the client data rate. Based on the averaged data rate, justification opportunities are added to the client data in each sub-stream, which are then multiplexed into frames that are output from the egress node. By including the justification opportunities, the effective rate of each sub-stream may be set equal to the original data rate when the sub-streams are demultiplexed after being output from the egress node. An advantage of the present disclosure is that the justification opportunities, are not generated based solely on clock signals generated by PLL circuits. As a result, fewer PLL circuits are required, thereby simplifying system design and minimizing power consumption.

Clocking of client signals output from an egress node in a network

Embodiments of the present invention compensate for skew across a wavelength division multiplexed network. The network is a wavelength division multiplexed optical transport network. The skew compensation can be performed electrically or optically. It can be performed on the transmission side of the network, the receiver side of the network or at any intermediary node on the network.

Communication network with skew compensation

Consistent with the present disclosure, a plurality of FIFO buffers, for example, are provided in a switch, which also includes a switch fabric. Each of the plurality of FIFOs is pre-filled with data for a duration based on a skew or time difference between the time that a data unit group is supplied to its corresponding FIFO and a reference time. The reference time is the time, for example, after a delay period has lapsed following the leading edge of a synch signal, the timing of which is a known system parameter and is used to trigger switching in the switch fabric. Typically, the delay period may be equal to the latency (often, another known system parameter) or length of time required for the data unit to propagate from an input circuit, such as a line card of the switch or another switch, to the FIFO that receives the data unit. At the reference time, temporally aligned data unit groups may be read or output from each FIFO and supplied to the switch fabric. Since the timing of the output from the FIFOs is based on known system parameters, instead of the actual arrival of the slowest data unit group at its corresponding FIFO, time aligned data unit groups may be output regardless of whether the slowest data unit group is available.

Temporal alignment of data unit groups in a switch

Embodiments of the present invention determine skew relative to a plurality of communication paths on a network system. The network is a wavelength division multiplexed optical transport network. The plurality of communication paths involves different signal and path attributes such as a plurality of carrier wavelengths, optical carrier groups, physical communication paths (different nodes, different fibers along a same path, or any combination of the foregoing), or any other differentiating factors between two paths.

Communication network with skew determination

Serial-to-parallel and parallel-to-serial conversion devices may provide for efficient conversion of serial bit streams into parallel data units (and vice versa). In one implementation, a device may include delay circuits, each of which being configured to receive a serial data stream. A rotator circuit may receive the delayed serial data streams and rearrange bits in the serial data streams. Register circuits may receive the output of the rotator circuit and collectively output, in parallel, a number of bits of one of the serial bit streams.

Devices for conversion between serial and parallel data

Embodiments of the present invention provide for diverse routing of a plurality of data streams, representative of a client signal of an unknown format, across multiple communication paths of a digital optical network through the use of a marker embedded in the client signal which is then inserted into the client payload portion of a transport frame. The multiple communication paths include different signal and path attributes related to the optical signals which transport the data streams across the digital optical network, as well as the physical structure of the digital optical network itself, all leading to timing variations in the multiple communication paths. The digital optical network transports the plurality of data streams in the form of wavelength division multiplexed signals, or banded wavelength division multiplexed signals.

Digital framer architecture with a framing marker

Embodiments of the present invention route a wavelength division multiplexed signal across multiple communication paths using skew characteristics of at least some of the communication paths. The network is a wavelength division multiplexed optical transport network. The plurality of communication paths involves different signal and path attributes such as a plurality of carrier wavelengths, optical carrier groups, physical communication paths (different nodes, different fibers along a same path, or any combination of the foregoing), or any other differentiating factors between two paths.

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Fremont, CA, United States of America

Prasad Paranjape