Patent ID: 7734178

Claim:
A passive optical network system which comprises an optical line terminal, an optical splitter, an optical fiber, and a plurality of optical network units connected to the optical line terminal through the optical splitter, and in which the optical line terminal and the optical network units communicate with each other by wavelength division multiplexing, wherein a first wavelength which is received in common by the respective optical network units is previously determined, and a second wavelength for communication between the optical line terminal and each of the optical network units is assigned to each of the optical network unit among a plurality of wavelengths which are different from the first wavelength, wherein the optical line terminal includes: a plurality of first transmitters each of which has a light source different from each other in wavelength; a plurality of first receivers to receive signals of a plurality of wavelengths; a wavelength management table to manage, for each of identifiers of the optical network units, second wavelength information assigned for communication with each of the optical network units; and a first control unit to transmit a control message for assigning the second wavelength to the optical network unit through one of the first transmitters, wherein each of the optical network units includes: two or three or more second receivers in which wavelengths different from each other are set and which respectively receive signals of the set wavelengths; one or a plurality of second transmitters to transmit signals of set wavelengths; a wavelength control unit to variably control transmission wavelengths of the second transmitters and reception wavelengths of the second receivers in accordance with stored wavelength information; and a second control unit to receive the control message for assigning the second wavelength from the optical line terminal through the second receiver and to store the second wavelength information assigned to the optical network unit itself into the wavelength control unit, wherein one of the first transmitters of the optical line terminal and one of the second receivers of the optical network units are previously set to the first wavelength, and wherein data of broadcast communication to the optical network units is transmitted by the first wavelength, and/or the control message including second wavelength information not assigned to other communications on the basis of the wavelength management table is transmitted to the optical network unit by the first wavelength, and the second wavelength is assigned to each of the optical network units.