DATA SERIES MODULATION METHOD, DATA SERIES DEMODULATION METHOD, STATION SIDE TERMINATOR, SUBSCRIBER SIDE TERMINATOR, AND PASSIVE OPTICAL NETWORK SYSTEM

摘要

PROBLEM TO BE SOLVED: To reduce an error rate of phase demodulation, in a multilevel/high order modulation system performing amplitude modulation and phase modulation in parallel for the same carrier signal.SOLUTION: An error rate of phase demodulation is reduced on the inside of a constellation, by decreasing the number of signal points of phase modulation on the inside of a constellation when compared with the outside of a constellation. On the outside of a constellation, transmission efficiency of the entire phase modulation signal is enhanced by increasing the number of signal points of phase modulation. The error rate of phase demodulation is reduced on the outside of a constellation, by not increasing the number of signal points of phase modulation more than required on the outside of a constellation. Reduction in the error rate of phase demodulation, and enhancement in the transmission efficiency of the entire phase modulation signal are balanced, by setting the number of signal points of phase modulation appropriately.