Patent Document ID: 20040131368
Application ID: 10416550
Patent Flag: 0

Claim One:
1. An optical receiver comprising: a photoelectric conversion means for converting an optical received signal into an electric received signal; a soft-decision deciding means for deciding the electric received signal obtained by said photoelectric conversion means according to a plurality of decision levels so as to output a multivalued decision signal; a demultiplexing means for serial-to-parallel converting the multivalued decision signal delivered from said soft-decision deciding means so as to output a multivalued parallel signal; a soft-decision error correction decoding means for making an error correction to the multivalued parallel signal delivered from said demultiplexing means based on reliability information so as to output an error-corrected parallel received signal and decision results indicating the decision of the electric received signal according to the plurality of decision levels; a probability density distribution estimation means for estimating probability density distributions based on distributions of the decision results indicating the decision of the information data according to the plurality of decision levels, which are delivered from said soft-decision error correction decoding means; and a decision level control means for controlling the plurality of decision levels in said soft-decision deciding means based on the probability density distributions estimated by said probability density distribution estimation means.