Upon receiving a communications signal conveying symbols at a symbol period T, a receiver applies filter coefficients to a digital representation of the communications signal, thereby generating filtered signals having a shape in the frequency domain characterized by a bandwidth expansion factor α, where components of the filtered signals correspond to angular frequencies $\omega =-\frac{\pi \left(1+\alpha \right)}{T}\mathrm{.Math.}-\frac{\pi \left(1-\alpha \right)}{T},+\frac{\pi \left(1-\alpha \right)}{T}\mathrm{.Math.}+\frac{\pi \left(1+\alpha \right)}{T}.$
The receiver calculates first-order components from a first phase derivative of the components at a first differential distance, second-order components from a second phase derivative of the first-order components at a second differential distance, and composite second-order components from an average of the second-order components over multiple time in

Upon receiving a communications signal conveying symbols at a symbol period T, a receiver applies filter coefficients to a digital representation of the communications signal, thereby generating filtered signals having a shape in the frequency domain characterized by a bandwidth expansion factor α, where components of the filtered signals correspond to angular frequencies $\omega =-\frac{\pi \left(1+\alpha \right)}{T}\mathrm{.Math.}-\frac{\pi \left(1-\alpha \right)}{T},+\frac{\pi \left(1-\alpha \right)}{T}\mathrm{.Math.}+\frac{\pi \left(1+\alpha \right)}{T}.$
The receiver calculates first-order components from a first phase derivative of the components at a first differential distance, second-order components from a second phase derivative of the first-order components at a second differential distance, and composite second-order components from an average of the second-order components over multiple time in

A master station device is connected to a slave station device that emits a transmission signal received by light via an optical transmission path from a plurality of antenna elements. The master station device includes an optical signal output unit that outputs optical signals of a plurality of wavelengths, a phase adjustment unit that adjusts, for each wavelength, a phase of the transmission signal based on phase rotation that the optical signal is to undergo while being transmitted through the optical transmission path and a phase in one of the antenna elements corresponding to the wavelength of the optical signal, an optical modulation unit that modulates, for each wavelength, the optical signal output by the optical signal output unit with the transmission signal the phase of which is adjusted in accordance with the wavelength of the optical signal, and an optical combining unit that multiplexes the optical modulated signal of each wavelength and outputs the multiplexed signal to the optical transmission path. The slave station device includes an optical demultiplexing unit that demultiplexes the optical modulated signal transmitted through the optical transmission path and an optical/electric conversion unit that outputs the transmission signal obtained by converting the optical modulated signal of each wavelength into an electric signal to one of the plurality of the antenna elements corresponding to the wavelength.

An optical receiving device that divides receive signals obtained by receiving an optical signal using a coherent detection scheme into a plurality of frequency bands, matches timing of the receive signals along a time axis between the frequency bands resulting from the division, performs a combining process of combining the receive signals contained in the plurality of frequency bands, and compensates the receive signals for waveform distortion either before or after the combining process, includes: a first wavelength dispersion compensation unit adapted to compensate the receive signals for waveform distortion in each of the frequency bands resulting from the division; a first nonlinear compensation unit adapted to compensate the receive signals belonging to each of the frequency bands and timed with each other in a time domain for a nonlinear optical effect; and a second wavelength dispersion compensation unit adapted to compensate the receive signals belonging to each of the frequency bands and compensated for the nonlinear optical effect for wavelength dispersion in each of the frequency bands.

An optical receiving device that divides receive signals obtained by receiving an optical signal using a coherent detection scheme into a plurality of frequency bands, matches timing of the receive signals along a time axis between the frequency bands resulting from the division, performs a combining process of combining the receive signals contained in the plurality of frequency bands, and compensates the receive signals for waveform distortion either before or after the combining process, includes: a first wavelength dispersion compensation unit adapted to compensate the receive signals for waveform distortion in each of the frequency bands resulting from the division; a first nonlinear compensation unit adapted to compensate the receive signals belonging to each of the frequency bands and timed with each other in a time domain for a nonlinear optical effect; and a second wavelength dispersion compensation unit adapted to compensate the receive signals belonging to each of the frequency bands and compensated for the nonlinear optical effect for wavelength dispersion in each of the frequency bands.

An optical fiber transmission system and method for using the system are provided. The system may include a span of transmission fiber for transmitting light signals through the optical fiber transmission system. The system may include a dispersion compensating module coupled to the span of transmission fiber. The system may include a switchable module including a set of selectable light signal paths, the set of selectable light signal paths including at least one path through a dispersion compensating element. The system may include a processor coupled to the switchable module for selectively monitoring the set of selectable light signal paths, where the processor is further configured to derive a metric based on the set of selectable light signal paths for controlling the dispersion compensating module.

In one example aspect, a A method is provided of dispersion compensation for an optical link includes , the method comprising establishing communication using a first symbol rate over the optical link, determining a dispersion compensation for the optical link based on the communication at the first symbol rate, and establishing communication using a second symbol rate over the optical link using the determined dispersion compensation, wherein the second symbol rate is higher than the first symbol rate.

In one example aspect, a A method is provided of dispersion compensation for an optical link includes , the method comprising establishing communication using a first symbol rate over the optical link, determining a dispersion compensation for the optical link based on the communication at the first symbol rate, and establishing communication using a second symbol rate over the optical link using the determined dispersion compensation, wherein the second symbol rate is higher than the first symbol rate.

A monitoring device includes a processor configured to compensate an electric field signal generated from an optical signal alternately for a chromatic dispersion and a nonlinear distortion in the optical signal in each of virtual sections of a transmission line, evaluate a quality of a compensated electric field signal, select the virtual sections sequentially, set a first compensation quantity of the chromatic dispersion according to a length of each of the virtual sections, search for a third compensation quantity of the nonlinear distortion for a selected virtual section when the quality satisfies a predetermined condition under an assumption that no nonlinear distortion is produced in other virtual sections, search for a second compensation quantity of the nonlinear distortion by setting an initial value of the second compensation quantity to the third compensation quantity, and monitor a power distribution of the optical signal based on the first and second compensation quantities.

A monitoring device includes a processor configured to compensate an electric field signal generated from an optical signal alternately for a chromatic dispersion and a nonlinear distortion in the optical signal in each of virtual sections of a transmission line, evaluate a quality of a compensated electric field signal, select the virtual sections sequentially, set a first compensation quantity of the chromatic dispersion according to a length of each of the virtual sections, search for a third compensation quantity of the nonlinear distortion for a selected virtual section when the quality satisfies a predetermined condition under an assumption that no nonlinear distortion is produced in other virtual sections, search for a second compensation quantity of the nonlinear distortion by setting an initial value of the second compensation quantity to the third compensation quantity, and monitor a power distribution of the optical signal based on the first and second compensation quantities.