Repeater and repeating method

Abstract

A repeater is disclosed that transmits an optical signal using wave division multiplexing. The repeater includes a demultiplexing unit that separates plural channels contained in the optical signal, an adjusting unit that adjusts at least optical power of each of the channels according to a control signal, a multiplexing unit that outputs a multiple wavelength signal in which the channels are multiplexed, and a monitoring unit that determines a modulation scheme and a bit rate of the optical signal for each of the channels so as to generate the control signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a repeater according to an embodiment of the present invention;

FIG. 2 is a detailed block diagram showing a monitoring part and an adjustment amount controlling part;

FIG. 3 is a flowchart showing a procedure of determining the adjustment amount of optical power according to an embodiment;

FIG. 4 shows an example of a measurement result of a multiple wavelength signal;

FIG. 5 is a graph showing an actual waveform and an approximate waveform;

FIGS. 6 and 7 provide a table showing spectrum characteristics of transmission schemes;

FIG. 8 is a table showing predetermined relationships between transmission schemes and peak values; and

FIG. 9 is a block diagram showing an example of an element for dispersion compensation.

Claims

1. A repeater that transmits an optical signal using wave division multiplexing, comprising: a demultiplexing unit that separates a plurality of channels contained in the optical signal;an adjusting unit that adjusts at least optical power of each of the channels according to a control signal;a multiplexing unit that outputs a multiple wavelength signal in which the channels are multiplexed; anda monitoring unit that determines a modulation scheme and a bit rate of the optical signal for each of the channels so as to generate the control signal.

2. The repeater as claimed in claim 1, wherein the adjusting unit includes an attenuator that attenuates the optical power.

3. The repeater as claimed in claim 1, wherein the adjusting unit includes a wavelength selection switching unit that selects one of the channels according to a control signal; anda unit that performs predetermined dispersion compensation on the channel selected by the wavelength selection switching unit.

4. The repeater as claimed in claim 1, wherein the monitoring unit includes a unit that detects peaks of the optical signal and calculates an approximate waveform that represents the optical signal with the peaks removed; anda unit that compares a waveform with the peaks and the approximate waveform so as to determine a candidate for the modulation scheme and a candidate for the bit rate of each of the channels.

5 The repeater as claimed in claim 4, wherein the approximate waveform is represented by a curve with a single extremum in a predetermined wavelength range.

6. The repeater as claimed in claim 5, wherein the approximate waveform is represented by a quadratic curve.

7. The repeater as claimed in claim 1, wherein the monitoring unit includes a unit that measures spectral widths of the optical signal and determines a candidate for the modulation scheme and a candidate for the bit rate of each of the channels.

8. The repeater as claimed in claim 1, wherein the monitoring unit includes a memory unit that stores relationships between the modulation schemes, the bit rates, peak values, and optical power integration values.

9. The repeater as claimed in claim 8, wherein the monitoring unit refers to the relationships and generates a control signal for the determined modulation scheme and the bit rate of each of the channels.

10. The repeater as claimed in claim 1, wherein the modulation schemes of the channels are intensity modulation or phase modulation.

11. The repeater as claimed in claim 10, wherein the modulation schemes of the channels are any one of NRZ, RZ, duobinary, and PSK.

12. The repeater as claimed in claim 1, wherein the bit rates of the channels are 10 Gbps or 40 Gbps.

13. A repeating method that transmits an optical signal using wave division multiplexing, comprising: a demultiplexing step of separating a plurality of channels contained in the optical signal;an adjusting step of adjusting at least optical power of each of the channels according to a control signal; anda multiplexing step of outputting a multiple wavelength signal in which the channels are multiplexed;wherein the control signal is generated by determining a modulation scheme and a bit rate of the optical signal for each of the channels.