MULTI-VALUE MODULATION SIGNAL GENERATING METHOD AND OPTICAL COMMUNICATION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a multi-value modulation signal generating method and an optical communication system that allow reception signals at an old ONU and a new ONU to satisfy predefined signal quality at the same time.SOLUTION: When a PD performs direct detection, using a star 8-QAM signal whose extinction ratio will be in a range of 6.1 dB to 12.3 dB allows all signals received by an old ONU and a new ONU to achieve BER<10E-03 at a reception sensitivity of -28 dBm or lower. An optical communication system comprises: an ONU of an IEEE 802.3av 10G-EPON or an ITU-T G.987-series XG-PON; a coherent receiver; and a DSP. Thereby, the optical communication system enables replacement of the ONU by an ONU capable of receiving an amplitude modulation component and a phase modulation component, and coexistence with it under the same OLT.