Patent ID: 8139940

Claim:
A wavelength division multiplexing transmission system in which a plurality of remote apparatuses are connected to a station apparatus which communicates with the remote apparatuses using a given plurality of wavelengths, wherein each of the remote apparatuses comprises: a receiver which receives transmissions from the station apparatus of one or more wavelengths of the given plurality of wavelengths; a wavelength separating device which separates, according to a wavelength control signal, a wavelength from the given plurality of wavelengths; a signal output device which outputs a reception status signal indicating whether or not a separated wavelength is received from the wavelength separating device; and a wavelength control device which generates the wavelength control signal to the wavelength separating device and receives a reception status signal to determine whether a signal corresponding to the separated wavelength is being received, and, if not, sets the separated wavelength as the wavelength to be used in the remote apparatus and wherein the remote apparatus transmits a signal having said separated wavelength to said station apparatus, but if it is determined that a signal corresponding to the separated wavelength is received, then generating a new wavelength control signal to control the wavelength separating device to separate a different wavelength from the given plurality of wavelengths until the wavelength control device determines that no signal corresponding to the separated different wavelength is being received, wherein when no signal corresponding to the separated different wavelength is being received the remote apparatus causes the station apparatus to be updated to include the separated different wavelength to be transmitted by the station apparatus with the given plurality of wavelengths.