# US 12,009,865 B2 · Optical transmitter, optical communication system, and optical communication method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,009,865 B2 - Document ID: US12009865B2 - Status: Granted - Kind: B2 - Application number: 17/899,786 - Filed: 2022-08-31 - Published: 2022-12-29 - Granted: 2024-06-11 - Earliest claimed: 2014-10-10 - Assignees: NEC Asia Pacific Pte Ltd. - Applicants: NEC Corporation - Inventors: Junichi Abe; Tatsuya Nakamura - Web page: https://patentgrep.com/patent/US12009865B2 ## CPC - H04B 10/516: Details of coding or modulation - H04B 10/541: {Digital intensity or amplitude modulation} - H04B 10/25891: {Transmission components (H04B10/40 takes precedence)} - H04B 10/5161: {Combination of different modulation schemes} - H04L 27/36: Modulator circuits; Transmitter circuits - H04L 27/38: Demodulator circuits; Receiver circuits - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract If a configuration is employed in which modulation schemes used for an optical communication system can be switched depending on transmission conditions, the power consumption increases and the control becomes complex; therefore, an optical transmitter according to an exemplary aspect of the present invention includes an encoding means for encoding digital signals to be transmitted under a predetermined transmission condition over an optical carrier wave by using one of a plurality of encoding methods; an encoding control means for selecting a predetermined encoding method corresponding to the predetermined transmission condition from among the plurality of encoding methods and causing the encoding means to operate in accordance with the predetermined encoding method; a mapping means for mapping output bit signals output from the encoding means to modulation symbols; and an optical modulation means for modulating the optical carrier wave based on symbol signals output from the mapping means. ## Claims ### Claim 1 An optical transceiver, comprising: an encoder configured to encode input digital signals by one of a plurality of encoding methods and output the encoded digital signals; a controller configured to control the encoder to select one of the plurality of encoding methods based on real-time optical transmission attributes of an optical carrier wave; a mapper configured to map the encoded digital signals to symbol signals and output the mapped symbol signals; and an optical modulator configured to modulate the optical carrier wave based on the mapped symbol signals. ### Claim 2 (depends on 1) The optical transceiver of claim 1, wherein the plurality of encoding methods comprises at least two of a BPSK (Binary Phase Shift Keying) encoding method, a QPSK (Quadrature Phase Shift Keying) encoding method, a 8QAM encoding method, or a 16QAM encoding method. ### Claim 3 (depends on 1) The optical transceiver according to claim 1, wherein the optical transmission attributes include at least one of a transmission capacity, a transmission distance, an error rate, or an optical signal-to-noise ratio. ### Claim 4 (depends on 1) The optical transceiver according to claim 1, wherein the controller is configured to change an encoding method to balance optical transmission distance and capacity of the digital signals. ### Claim 5 (depends on 1) The optical transceiver according to claim 1, wherein the controller is configured to change an encoding method in real time corresponding to real-time optical transmission measurements. ### Claim 6 (depends on 1) The optical transceiver according to claim 1, wherein the controller is configured to set drive signals to modulate the optical carrier wave. ### Claim 7 (depends on 1) The optical transceiver according to claim 1, wherein the symbol signals include at least one dimension of dimensions including optical phase, polarization, or wavelength of the optical carrier wave, or time. ### Claim 8 (depends on 1) The optical transceiver of claim 1, wherein the plurality of encoding methods includes a QAM (Quadrature Amplitude Modulation) encoding method; and wherein the mapper is further configured to map the encoded digital signals to one of a plurality of partial constellations obtained by dividing a constellation of the QAM encoding method. ### Claim 9 (depends on 8) The optical transceiver of claim 8, wherein the plurality of partial constellations include a decreased number of symbol signals or an increased distance between the symbol signals with respect to the constellation of the QAM encoding method. ### Claim 10 An optical communication method, comprising: encoding input digital signals by one of a plurality of encoding methods and outputting the encoded digital signals; controlling the encoding to select one of the plurality of encoding methods based on real-time optical transmission attributes of an optical carrier wave; mapping the encoded digital signals to symbol signals and outputting the mapped symbol signals; and modulating the optical carrier wave based on the mapped symbol signals. ### Claim 11 (depends on 10) The optical communication method according to claim 10, wherein the plurality of encoding methods comprises at least two of a BPSK (Binary Phase Shift Keying) encoding method, a QPSK (Quadrature Phase Shift Keying) encoding method, a 8QAM encoding method, or a 16QAM encoding method. ### Claim 12 (depends on 10) The optical communication method according to claim 10, wherein the optical transmission attributes include at least one of a transmission capacity, a transmission distance, an error rate, or an optical signal-to-noise ratio. ### Claim 13 (depends on 10) The optical communication method according to claim 10, wherein the controlling the encoding includes changing an encoding method to balance optical transmission distance and capacity of the digital signals. ### Claim 14 (depends on 10) The optical communication method according to claim 10, wherein the controlling the encoding includes changing an encoding method in real time corresponding to real-time optical transmission measurements. ### Claim 15 (depends on 10) The optical communication method according to claim 10, further comprising setting drive signals to modulate the optical carrier wave. ### Claim 16 (depends on 10) The optical communication method according to claim 10, wherein the symbol signals include at least one dimension of dimensions including optical phase, polarization, or wavelength of the optical carrier wave, or time. ### Claim 17 (depends on 16) The optical communication method according to claim 16, wherein the plurality of encoding methods includes a QAM (Quadrature Amplitude Modulation) encoding method; and wherein the optical communication method further comprises mapping the encoded digital signals to one of a plurality of partial constellations obtained by dividing a constellation of the QAM encoding method. ### Claim 18 (depends on 17) The optical communication method according to claim 17, wherein the plurality of partial constellations include a decreased number of symbol signals or an increased distance between the symbol signals with respect to the constellation of the QAM encoding method.