| 摘要 |
PROBLEM TO BE SOLVED: To provide a system achieving economical high speed large capacity and flexible adaptive modulation, without complicating the configuration and without making the device expensive, in a time sharing multiplex access system and/or wavelength multiplex access system.SOLUTION: A PAM adaptive modulation OLT3 performs PAM modulation of multiple value greater than binary having a multiple value level depending on the transmission distance, for a downlink signal transmitted to an ONU4, and PAM modulation of multiple value greater than binary having a multiple value level depending on the transmission distance, for an uplink signal received from the ONU4. The ONU4 performs PAM demodulation of multiple value greater than binary having a multiple value level depending on the transmission distance, for a downlink signal received from the PAM adaptive modulation OLT3, and PAM modulation of multiple value greater than binary having a multiple value level depending on the transmission distance, for an uplink signal transmitted to the PAM adaptive modulation OLT3. |
