Patent ID: 7627256
Filing Date: 2009-12-01
Classification: H04B,H04J

Abstract:
1. A wavelength division multiplexed optical signal transmission method, comprising: transmitting via one or more optical repeaters a wavelength division multiplexed optical signal composed of a control optical signal and a plurality of controlled optical signals from an upstream device to a downstream device through optical fibers; in the optical repeater, demultiplexing a wavelength division multiplexed optical signal transmitted from the upstream device into optical signals each having a different wavelength; processing the controlled optical signals of different wavelengths individually based on the control optical signal that contains wavelength number information indicating the presence or absence of a controlled optical signal with respect to each wavelength; remultiplexing the control optical signal and the controlled optical signals that have undergone the processing to obtain a wavelength division multiplexed optical signal; and transmitting the wavelength division multiplexed optical signal to the downstream device, wherein: in the case where the wavelength number information provides a signal present indication corresponding to a controlled optical signal, when the signal has not deteriorated, the optical repeater allows the signal to pass through without changing the signal present indication of the wavelength number information, while, when the signal has deteriorated, the optical repeater once terminates the signal and regenerates a controlled optical signal to allow the new signal regenerated from the deteriorated signal to pass through without changing the signal present indication of the wavelength number information; and in the case where the wavelength number information provides a signal absent indication corresponding to a controlled optical signal, when receiving an optical signal from the outside, the optical repeater outputs the optical signal as the controlled optical signal and updates the wavelength number information to indicate the presence of the signal, while, when receiving no optical signal from the outside, the optical repeater terminates the controlled optical signal without changing the signal absent indication of the wavelength number information.