Abstract: A receiver configured to receive a plurality of symbols is disclosed. The receiver includes a hard decision decoder, a look-up table (LUT) coupled to the hard decision decoder, and a soft metric generator coupled to the LUT. The hard decision decoder is to receive a first set of symbols from the plurality of symbols and provide a set of hard coded neighboring symbols to the LUT. The first set of symbols comprises a center symbol with neighboring symbols. The LUT is to store a value representative of the center symbol that is addressable by the set of hard coded neighboring symbols. The soft metric generator is to calculate bit log likelihood ratio (LLR) values based on the center symbol and the value representative of the center symbol stored in the LUT.

Abstract: A coding scheme is provided transporting encoded information over an optical communications link to a network. Multi-word information groups are analyzed to determine whether each of the information groups includes control characters. If the information group does not include any control characters, an encoded information stream including a set data indicator and data words is generated. If the information group includes one or more control characters, an encoded information stream is generated which includes control code counters, a transition indicator, location pointers, control codes that are encoded from the control characters, and any data. Accordingly, the necessary bandwidth for transporting the information is reduced by using this encoded information stream without sacrificing any control information.

Abstract: A method is provided for optical filter card design that facilitates a relatively efficient filter assignment algorithm solution resulting in a filter design that reduces a probability of unnecessary wavelength regenerations.

Abstract: An optical amplifier for a 4-fiber system having two inputs and outputs is provided that makes use of a single amplifier rather than two separate amplifiers. The optical amplifier node makes use of an interleaver before and after the single amplifier to demultiplex and multiplex even and odd channel signals traveling in opposite directions. The arrangement can also amplify wide channel spaced signals traveling through a plurality of optical fibers. The optical amplifier node can be combined with other like amplifier nodes to provide more complex amplifier solutions at reduced costs due to the need for only half of the typical number of amplifiers. The optical amplifier node can also be combined with, e.g., variable optical attenuators, L/C/S filters, channel add/drop, co- and counter-propagating Raman amplification, and dispersion compensation modules to modify the optical signals as desired.

Abstract: A method is provided for optical filter card design that facilitates a relatively efficient filter assignment algorithm solution resulting in a filter design that reduces a probability of unnecessary wavelength regenerations.

Abstract: A coding scheme is provided for transporting information over an optical communications link to a network. Information containing data and control characters is encoded after segmenting the information into multi-word information groups and determining whether each of the information groups includes control characters. If the information group does not include any control characters, an encoded information stream including a set data indicator and data words is generated. If the information group includes one or more control characters, the control characters are encoded to control codes and a control code map is generated for representing placement positions of the control characters within the information group. Then, an encoded information stream is generated to include the control code map combined with one of the control codes as well as the remaining control codes and/or data words.

Abstract: A coding scheme is provided transporting encoded information over an optical communications link to a network. Multi-word information groups are analyzed to determine whether each of the information groups includes control characters. If the information group does not include any control characters, an encoded information stream including a set data indicator and data words is generated. If the information group includes one or more control characters, an encoded information stream is generated which includes control code counters, a transition indicator, location pointers, control codes that are encoded from the control characters, and any data. Accordingly, the necessary bandwidth for transporting the information is reduced by using this encoded information stream without sacrificing any control information.

Abstract: An optical amplifier for a 4-fiber system having two inputs and outputs is provided that makes use of a single amplifier rather than two separate amplifiers. The optical amplifier node makes use of an interleaver before and after the single amplifier to demultiplex and multiplex even and odd channel signals traveling in opposite directions. The arrangement can also amplify wide channel spaced signals traveling through a plurality of optical fibers. The optical amplifier node can be combined with other like amplifier nodes to provide more complex amplifier solutions at reduced costs due to the need for only half of the typical number of amplifiers. The optical amplifier node can also be combined with, e.g., variable optical attenuators, L/C/S filters, channel add/drop, co- and counter-propagating Raman amplification, and dispersion compensation modules to modify the optical signals as desired.

Abstract: A Dense Wavelength Division Multiplexed (DWDM) optical transmission system that compensates for unequal channel performance over an extended fiber transmission distance.

Abstract: A high speed DWDM optical transmission system that reduces a fiber dispersion limit without reducing the total channel count of a multi-wavelength optical signal. The system achieves such reduction in the fiber dispersion limit by employing a multi-wavelength optical signal comprising a gap-free band structure, and performing per-band dispersion compensation on the optical signal by adjusting residual dispersion values associated with one or more of the bands. In one embodiment, the system includes a first dispersion compensation module (DCM) that provides a dispersion-compensated multi-wavelength optical signal containing wavelength-dependent residual dispersion to a band splitter. The band splitter separates the dispersion-compensated optical signal into a plurality of bands such that no band gaps are formed between adjacent bands, and provides each band to a respective second DCM configured to reduce the residual dispersion associated with that band to a predetermined range of residual dispersion values.

Abstract: In an optical communications network, an optical add/drop node that is flexible to support changing traffic demands, and also induces little loss to the signal. The optical add/drop node of the present invention utilizes a filter that is capable of adding and dropping wavelengths across different bands in a multiplexed signal. The Optical Add/Drop Node of the invention is flexible to adjust with changing traffic demands by reserving bandwidth for future use. The present invention provides immediate scalability to the optical network without requiring reconfiguration of the network architecture. In addition to providing flexibility for future expansion, the invention also reduces loss to the signal passing through the network. This is accomplished by reducing the number of connection points in the filter relative to an alternative flexible add/drop solution.

Abstract: Data transmission apparatus includes first and second optical transmitters coupled to an optical link. A forward error correction (FEC) coder is coupled to the input of the second optical transmitter. A first information signal having a first information rate is provided to the first optical transmitter, and a second information signal having a second information rate is provided to the second optical transmitter. The use of the FEC coder enables the second information signal to have a higher information rate than the first information signal, while simultaneously enabling the respective output power levels of the first and second optical amplifiers to be substantially equal. The data transmission apparatus achieves higher data transmission capacity while retaining compatibility with pre-existing fiber spans and amplifier nodes.

Abstract: Multiple gigabit Ethernet (GbE) and Fiber Channel (FC) signals are multiplexed and transported on a wavelength-division multiplexed (WDM) communications link using synchronous optical network (SONET) signaling. A transmitter decodes the 8b/10b encoded GbE/FC signals to reduce their respective signaling rates to no greater than the payload data rate of an OC-48 signal used on the link. The decoded signal are packetized into fixed-size packets in order to append a stream identifier used for de-multiplexing at the receive end. The packetized streams are multiplexed together and formatted into the OC-48 signal, which is transmitted over the communications link. A receiver de-multiplexes the received signal to obtain the packet streams, converts the packet streams to the corresponding decoded signals, and re-encodes each signal to re-create the original GbE/FC signals. A pair of interfaces can be arranged to provide independent adding or dropping of the GbE/FC signals that share the same wavelength.

Abstract: A system is provided for protecting a wavelength division multiplexing optical communications network against communication failures at the link, wavelength and fiber layers. The system includes failure detectors for detecting communication failures of the network and for generating failure signals in response thereto, and protection switching elements for receiving the failure signals and controlling the protection switching in response thereto. The system also includes a first set of intralayer communication channels within each of the link, wavelength and fiber layers for sending the failure signals between the failure detectors and the protection switching elements, and a second set of interlayer communication channels between adjacent ones of the link, wavelength and fiber layers for sending the failure signals between the failure detectors and the protection switching elements.

Abstract: An optical amplifier for a 4-fiber system having two inputs and outputs is provided that makes use of a single amplifier rather than two separate amplifiers. The optical amplifier node makes use of an interleaver before and after the single amplifier to demultiplex and multiplex even and odd channel signals traveling in opposite directions. The optical amplifier node can be combined with other like amplifier nodes to provide more complex amplifier solutions at reduced costs due to the need for only half of the typical number of amplifiers. The optical amplifier node can also be combined with, e.g., variable optical attenuators, L/C filters, channel add/drop, and dispersion compensation modules to modify the optical signals as desired.

Abstract: Methods for allocating connections between nodes in an optical ring communications network are provided. In these methods, working path connections are assigned so that the combination of required wavelengths and wavelength interface cards (WICs) in the network is minimized. In one such method, the wavelengths for the working path connections are assigned so that lightpaths are connected around the ring to complete a circle. In another method, components of lightpaths are connected so that a linked component group of lightpaths is formed around the ring until no more connectable lightpath connections are available or until a complete circle is formed around the ring.

Abstract: A high speed DWDM optical transmission system that reduces a fiber dispersion limit without reducing the total channel count of a multi-wavelength optical signal. The system achieves such reduction in the fiber dispersion limit by employing a multi-wavelength optical signal comprising a gap-free band structure, and performing per-band dispersion compensation on the optical signal by adjusting residual dispersion values associated with one or more of the bands. In one embodiment, the system includes a first dispersion compensation module (DCM) that provides a dispersion-compensated multi-wavelength optical signal containing wavelength-dependent residual dispersion to a band splitter. The band splitter separates the dispersion-compensated optical signal into a plurality of bands such that no band gaps are formed between adjacent bands, and provides each band to a respective second DCM configured to reduce the residual dispersion associated with that band to a predetermined range of residual dispersion values.

Abstract: A Dense Wavelength Division Multiplexed (DWDM) optical transmission system that compensates for unequal channel performance over an extended fiber transmission distance.

Abstract: A method and system for encoding signaling information at a physical layer of a network protocol, for example, an Ethernet-based protocol such as Gigabit Ethernet (GE). On a first network device, the signaling information may be encoded and multiplexed with data encoded according to a first block coding scheme to produce a stream of data encoded according to the first block coding scheme. The signaling information may be encoded using bit sequences not defined for use by the block first block coding scheme. This stream of data then may be transmitted on a network medium to another network device, which then may extract the bit sequences encoding the signaling information from the stream of data and decode the bit sequences into the signaling information. For two devices exchanging data on a first channel, signaling information may be multiplexed within this first channel itself, rather than sent on a separate channel.