Code division multiplexing optical access network system

An optical access network system in which a star coupler is provided at one end of an optical fiber channel and which performs two-way optical communications using code division multiplexing between an optical line terminal that is joined to the other end of said optical fiber channel and a plurality of optical network units respectively joined to a plurality of branched optical fiber channels that are formed branched by said star coupler,

• wherein said optical line terminal comprises a bandwidth allocation section and a bandwidth control section comprising signal converter pairs in a number equal to the number of said optical network units,
• each of said optical network units comprises a bandwidth allocation section and a bandwidth control section that comprises one set of signal converter pairs,
• each of said signal converter pairs is installed as one set of a variable serial to parallel conversion unit and a variable parallel to serial conversion unit each having a variable bandwidth management function, and
• said bandwidth allocation section comprises an encoder group that comprises a plurality of encoders that encode parallel signals that are output by said variable serial to parallel conversion unit and a parallel signal multiplexer that multiplexes said parallel signals that are output by said encoder group, a decoder group that comprises a plurality of decoders that decode parallel signals that are input to said variable parallel to serial conversion unit, and a serial signal distributor that divides the serial signal for generating the parallel signals that are input to said decoder group.