Optical wavelength multiplexing access system

A method of assigning wavelengths for an optical TX/RX device in a network including a plurality of optical TX/RX devices capable of varying respective upstream and downstream wavelengths, and an optical line terminal connected with the plurality of optical TX/RX devices via a power splitter, wherein each optical TX/RX device comprises a memory including a correspondence table between downstream wavelengths and upstream wavelengths, the method comprising:

• (a) detecting downstream wavelengths not in use by detecting presence or absence of the downstream wavelengths from the optical line terminal via the power splitter;
• (b) selecting one of the detected downstream wavelengths;
• (c) selecting an upstream wavelength corresponding to the selected downstream wavelength based on the correspondence table in the memory;
• (d) transmitting a signal light on the selected upstream wavelength;
• (e) detecting a response to the transmitted signal light on the selected downstream wavelength;
• and
• (f) initiating communication with the optical line terminal using the selected downstream wavelength and the selected upstream wavelength if the response is detected.

An optical TX/RX device for transmitting and receiving wavelength-multiplexed signal light, comprising:

• an optical RX means capable of varying a RX wavelength;
• an optical TX means capable of varying a TX wavelength;
• a detection means for detecting RX wavelengths not in use via the optical RX means;
• a storage means provided with a correspondence table between the RX wavelengths selectable for the optical RX means and the TX wavelengths selectable for the optical TX means;
• and
• a wavelength control means for assigning one of the RX wavelengths detected by the detection means to the RX wavelength of the optical RX means and for assigning a TX wavelength corresponding to the RX wavelength assigned based on the correspondence table in the storage means to the TX wavelength of the optical TX means,
• wherein
• the optical TX means transmits an optical signal on the assigned TX wavelength,
• the optical RX means receives a response signal to the optical signal on the assigned RX wavelength,
• the optical TX/RX device initiates communication using the optical TX means with the assigned TX wavelength and the optical RX means with the assigned RX wavelength if the optical RX means receives the response signal, and
• the optical TX/RX device is configured to detect the wavelengths not in use by the detection means, to assign one of the detected RX wavelengths to the RX wavelength of the optical RX means by the wavelength control means, and to assign a TX wavelength corresponding to the RX wavelength to the TX wavelength of the optical TX means, after a random period of time has elapsed, if the optical RX means receives no response signal.

An optical TX/RX device for transmitting and receiving wavelength-multiplexed signal light, comprising:

• an optical RX means capable of varying a RX wavelength;
• an optical TX means capable of varying a TX wavelength;
• a detection means for detecting RX wavelengths not in use via the optical RX means;
• a storage means provided with a correspondence table between the RX wavelengths selectable for the optical RX means and the TX wavelengths selectable for the optical TX means;
• and
• a wavelength control means for assigning one of the RX wavelengths detected by the detection means to the RX wavelength of the optical RX means and for assigning a TX wavelength corresponding to the RX wavelength assigned based on the correspondence table in the storage means to the TX wavelength of the optical TX means,
• wherein
• the optical TX means transmits an optical signal on the assigned TX wavelength,
• the optical RX means receives a response signal to the optical signal on the assigned RX wavelength,
• the optical TX/RX device initiates communication using the optical TX means with the assigned TX wavelength and the optical RX means with the assigned RX wavelength if the optical RX means receives the response signal, and
• the optical TX/RX device is configured to detect the wavelengths not in use by the detection means, to randomly assign one of the detected RX wavelengths to the RX wavelength of the optical RX means by the wavelength control means, and to assign a TX wavelength corresponding to the RX wavelength to the TX wavelength of the optical TX means, if the optical RX means receives no response signal.