Communication method, communication apparatus and communication system

A communication apparatus comprising:

• a previous-stage transmitter configured to acquire downlink optical signals having one or more wavelengths including a predetermined reception wavelength from a previous stage and transmit a communication situation signal or an allocation request signal of the communication apparatus to the previous stage using uplink optical signals having one or more wavelengths including a predetermined transmission wavelength;
• a selector configured to select a downlink optical signal having the reception wavelength;
• a receiver configured to acquire an allocation control signal indicating allocation of the reception wavelength and the transmission wavelength from the selected downlink optical signal having the reception wavelength;
• an extension-station-specific controller configured to update the reception wavelength and the transmission wavelength in accordance with the acquired allocation control signal;
• and
• a transmitter configured to transmit the uplink optical signals having the one or more wavelengths including the updated transmission wavelength to the previous stage using the previous-stage transmitter.

A communication system including a first-stage aggregate station and a plurality of extension stations connected in multiple stages including a last stage,

• wherein the aggregate station comprises
• an aggregate-station-specific transmitter configured to transmit downlink optical signals having one or more wavelengths including a predetermined reception wavelength to the plurality of extension stations;
• an aggregate-station-specific receiver configured to acquire uplink optical signals having one or more wavelengths, including a predetermined transmission wavelength, from the plurality of extension stations;
• and
• an aggregate-station-specific controller configured to generate an allocation control signal indicating allocation of the reception wavelength and the transmission wavelength on the basis of a communication situation signal or an allocation request signal of the extension station and include the allocation control signal in the downlink optical signals having the one or more wavelengths including the reception wavelength, and
• wherein the extension station comprises
• a previous-stage transmitter configured to acquire downlink optical signals having one or more wavelengths including the reception wavelength from a previous stage and transmit a communication situation signal or an allocation request signal of the extension station to the previous stage using uplink optical signals having one or more wavelengths including the transmission wavelength;
• a selector configured to select a downlink optical signal having the reception wavelength;
• an extension-station-specific receiver configured to acquire the allocation control signal from the selected downlink optical signal having the reception wavelength;
• an extension-station-specific controller configured to update the reception wavelength and the transmission wavelength in accordance with the acquired allocation control signal;
• and
• an extension-station-specific transmitter configured to transmit the uplink optical signals having the one or more wavelengths including the updated transmission wavelength to the previous stage using the previous-stage transmitter.