Optical transmission and reception system, optical transmitting and receiving apparatus, and optical transmission and reception method

An optical transmission and reception system including a first transmitting apparatus and a second transmitting apparatus each of which is a transmitting apparatus for converting a plurality of tributary signals into a single beam of multilevel modulated light for transmission, and a first receiving apparatus and a second receiving apparatus each of which is a receiving apparatus for receiving multilevel modulated light and converts it into a plurality of tributary signals, the optical transmission and reception system comprising:

• a first circuitry comprising,
• a polarization multiplexer to multiplex the multilevel modulated light transmitted by the first transmitting apparatus and the multilevel modulated light transmitted by the second transmitting apparatus so that the beams of multilevel modulated light are polarized orthogonal to each other, and to transmit the resultant as a multiplexed signal,
• a frequency offset controller to control to a predetermined value a difference in wavelength between the multilevel modulated light transmitted by the first transmitting apparatus and the multilevel modulated light transmitted by the second transmitting apparatus, and
• when receiving a multiplexed signal, an optical splitter to split the multiplexed signal and to output the split signals to the first receiving apparatus and the second receiving apparatus, respectively;
• each transmitting apparatus comprising,
• a second circuitry comprising,
• an error correction coder to apply error correction coding to each individual one of the tributary signals, the error correction coding including addition of a tributary identifier for identifying a tributary,
• a transmission-side rate converter to perform rate conversion by adding predetermined data to the signals given the error correction coding so that the signals have the same transmission rate, and
• a multilevel modulator to convert the signals rate-converted by the transmission-side rate converter into a single beam of multilevel modulated light;
• each receiving apparatus comprising,
• a third circuitry comprising,
• a multilevel modulated light receiver to receive multilevel modulated light, separate a received signal into tributary signals, and output the separated signals as received tributary signals to respective different output systems,
• a reception-side rate converter to perform rate conversion by deleting the predetermined data from the received tributary signals,
• an error correction decoder to perform error correction decoding on received tributary signals non-rate-converted by the reception-side rate converter or the received tributary signals rate-converted by the reception-side rate converter and extract the tributary identifiers from the received non-rate-converted tributary signals or the received rate converted tributary signals in respective different output systems,
• a tributary detector to retain tributary identifiers defined for the respective output systems in advance as output system tributary identifiers, compare the output system tributary identifier of each output system with the tributary identifier that is extracted from the received tributary signal output to the output system, and make a notification as to a match or mismatch as a result of comparison,
• a tributary selector to give an instruction to change correspondence between the received tributary signals and the output systems if the result of comparison is a mismatch, and
• the multilevel modulated light receiver changing the correspondence between the received tributary signals to output and the output systems based on the instruction from the tributary selector.

An optical transmission and reception method of an optical transmission and reception system, the system including a transmitting apparatus for converting a plurality of tributary signals into a single beam of multilevel modulated light for transmission and an optical receiving apparatus whose receiving apparatus receives multilevel modulated light and converts it into a plurality of tributary signals, the method comprising:

• performing error correction coding, using a circuitry, to cause the transmitting apparatus to apply error correction coding to each individual one of the tributary signals, the error correction coding including addition of a tributary identifier for identifying a tributary;
• performing transmission-side rate conversion, using the circuitry, to cause the transmitting apparatus to perform rate conversion by adding predetermined data to the signals given the error correction coding so that the signals have the same transmission rate;
• performing multilevel modulation, using the circuitry, to cause the transmitting apparatus to convert the signals rate-converted in the transmission-side rate conversion into a single beam of multilevel modulated light;
• receiving multilevel modulated light, using the circuitry, to cause the receiving apparatus to receive multilevel modulated light, separate a received signal into tributary signals, and output the separated signals as received tributary signals to respective different output systems;
• performing reception-side rate conversion, using the circuitry, to cause the receiving apparatus to perform rate conversion by deleting the predetermined data from the received tributary signals;
• performing error correction decoding, using the circuitry, to cause the receiving apparatus to perform error correction decoding on received tributary signals non-rate-converted in the reception-side rate conversion or the received tributary signals rate-converted in the reception-side rate conversion and extract the tributary identifiers from the received non-rate-converted tributary signals or the received rate-converted tributary signals in respective different output systems;
• performing tributary detection, using the circuitry, to cause the receiving apparatus to retain tributary identifiers defined for the respective output systems in advance as output system tributary identifiers, compare the output system tributary identifier of each output system with the tributary identifier that is extracted from the received tributary signal output to the output system, and make a notification as to a match or mismatch as a result of comparison;
• selecting a tributary, using the circuitry, to cause the receiving apparatus to give an instruction to change correspondence between the received tributary signals and the output systems if the result of comparison is a mismatch;
• and
• performing output change, using the circuitry, to cause the receiving apparatus to change the correspondence between the received tributary signals to output and the output systems based on the instruction.