When a frequency deviation compensation amount is compensated for by use of frequency shift, a phase offset occurs between adjacent input blocks included in a plurality of input blocks as divided, with the result that an error occurs in a reconstructed bit sequence. A frequency deviation compensation system of the invention is characterized by comprising: a frequency deviation compensation means for compensating for a frequency deviation occurring in a signal by use of frequency shift; and a phase offset compensation means for compensating for a phase offset occurring, in the signal, due to the frequency shift.

An information handling system includes a plurality of network nodes and a processor. The network nodes each include an optical link and a reflectometry analyzer. The reflection analyzers provide reflectometry results that each provide a characterization of physical properties of the associated optical link. The processor receives the reflectometry results, and, for each optical link, analyzes the reflectometry results to determine a fingerprint of the physical properties of the associated optical link. The processor further determines a status for each of the optical links based upon the associated fingerprints, and displays a map of the information handling system including each network node and the associated optical link, wherein the map provides an indication of the status for each of the optical links.

Methods, apparatus and non-transitory machine-readable mediums are provided for wireless communication in communication networks enabled for wireless light communication. In one embodiment, a method is performed in a node of a communication network. The method enables data communication to be established between a first wireless device and the communication network upon a wireless Light Communication (LC) link between the first wireless device and an LC-enabled Access Point (AP) of the communication network becoming unavailable. The method comprises: identifying a second wireless device for relaying data between the first wireless device and the communication network via a first communication link between the first wireless device and the second wireless device and a second communication link between the second wireless device and an AP of the communication network associated with the second wireless device.

In order to estimate a polarization fluctuation speed with high accuracy independently of the quality of a received signal, a polarization-fluctuation estimating device according to the present invention includes: a polarization de-multiplexing unit that generates a single-polarization optical signal from an input polarization-multiplexed optical signal; a photoelectric converting unit that converts the generated optical signal into an electrical signal; and an estimation unit that estimates the polarization fluctuation speed of the polarization-multiplexed optical signal in accordance with the electrical signal.

The disclosed systems and methods for monitoring, by a coherent optical monitor (OPM), generalized optical signal-to-noise ratio (gOSNR) of an optical channel, the method comprising: i) receiving, by an input port of the coherent OPM, a first signal and a second signal, wherein: the first signal and the second signal include same data, the first signal is an optical signal received from the optical channel, and the first signal is affected by a noise; ii) processing, by a digital signal processor (DSP) of the coherent OPM, the first signal and the second signal and extract the data from the first signal and the second signal; iii) computing, by the DSP, a first correlation between the data from the first signal and the data from the second digital signal; and iv) computing, by the DSP, a first gOSNR based on the first correlation.

A monitoring system according to the present disclosure includes: an optical fiber (10) configured to sense a peripheral environmental state, a monitor's terminal (40), a receiving unit (20) configured to receive an optical signal containing information indicating the environmental state from the optical fiber (10), a detecting unit (32) configured to detect at least one of an accident and an incident, based on the information indicating the environmental state, being included in the optical signal, and a broadcasting unit (33) configured to broadcast that the accident or the incident has occurred to the monitor's terminal (40) when the detecting unit (32) determines that the accident or the incident has occurred.

A method includes determining a first power level by performing a first series of measurements based on a first series of burst transmissions from an optical transmitter of an optical network unit (ONU) in an optical network. Bursts in the first series of burst transmissions include a first modified preamble. A second power level is determined by performing a second series of measurements based on a second series of optical burst transmissions. Bursts in the second series of burst transmissions include a second modified preamble. A first power level (Po) and a second power level (P.sub.1) are determined based on the first power level and the second power level and one or more additional parameters associated with transmissions from the optical transmitter are determined based on P.sub.0 and P.sub.1. Based on the additional parameters, it is determined whether the optical transmitter complies with specifications of the optical network.

Provided is a communication device that can deliver an improvement in the communication capacity of communication infrastructure with the quality of communication taken into consideration. A communication device includes an acquiring unit configured to acquire quality information of a communication line extending from a first communication device to a second communication device and including an optical communication line, an estimating unit configured to estimate the quality of communication of the second communication device and determine the required quality of communication of the second communication device based on the quality information, and a controlling unit configured to perform control on communication channels in the optical communication line so that the quality of communication satisfies the required quality of communication.

In a coherent optical receiver device, the dynamic range considerably decreases in the case of selectively receiving the optical multiplexed signals by means of the wavelength of the local oscillator light, therefore, a coherent optical receiver device according to an exemplary aspect of the invention includes a coherent optical receiver receiving optical multiplexed signals in a lump in which signal light is multiplexed; a variable optical attenuator; a local oscillator connected to the coherent optical receiver; and a first controller controlling the variable optical attenuator by means of a first control signal based on an output signal of the coherent optical receiver; wherein the coherent optical receiver includes a 90-degree hybrid circuit, a photoelectric converter, and an impedance conversion amplifier, and selectively detects the signal light interfering with local oscillation light output by the local oscillator out of the optical multiplexed signals; and the variable optical attenuator is disposed in the optical path of the optical multiplexed signals in a stage preceding the photoelectric converter, inputs the optical multiplexed signals, and outputs them to the coherent optical receiver controlling the intensity of the optical multiplexed signals based on the first control signal.

An electrical layer subnetwork connection protection includes determining, by a network device including a processor, signal status information based on a power of an obtained optical signal. The signal status information is used to indicate a state of a subnetwork connection carrying the optical signal. The method also includes filtering, by the network device, the signal status information based on a preset first threshold. The first threshold indicates a minimum duration in which the optical signal is in a valid state. The method further includes determining, by the network device based on the filtered signal status information, whether to switch a currently used first clock to a second clock different from the clock. The first clock or the second clock is used to initialize connection monitoring information in response to the determination of whether to switch the currently used first clock to the second clock.