Optical transmission system and optical transmission method

Abstract

After implementing a scrambler upon an electric signal of digital signals to be transmitted to a user terminal, this electric signal is converted into a digital optical signal, and an analog optical signal and this digital optical signal are multiplexed by wavelength division multiplexing, thereby reducing influence of cross-talk interference that is exerted on the analog optical signal by the digital optical signal.

1 . An optical transmission system comprising:
 a wavelength division multiplexing unit multiplexing, by wavelength division multiplexing, a first optical signal to be transmitted to a user terminal and a second optical signal to be transmitted to the user terminal, and transmitting the multiplexed signals to the side of the user terminal; and   a branching unit installed at such a degree of distance from the wavelength division multiplexing unit as to make ignorable cross-talk influence of the first optical signal upon the second optical signal in the multiplexed optical signals, branching the optical signals transmitted from the wavelength division multiplexing unit into a plurality of optical transmission paths, and transmitting the branched optical signals to the sides of the user terminals.   
     
     
         2 . An optical signal system comprising:
 plurality of wavelength division multiplexing unit multiplexing, by wavelength division multiplexing, first optical signals to be transmitted to user terminals and second optical signals to be transmitted to the user terminals, and transmitting the multiplexed signals to the sides of the user terminals;   a first branching unit branching and thus transmitting the first optical signals to the plurality of wavelength division multiplexing unit; and   a second branching unit branching and thus transmitting the second optical signals to the plurality of wavelength division multiplexing unit,   wherein the wavelength division multiplexing unit multiplexes the optical signals transmitted from the first branching unit and from the second branching unit.   
     
     
         3 . An optical transmission method comprising:
 wavelength division multiplexing unit multiplexes, by wavelength division multiplexing, a first optical signal to be transmitted to a user terminal and a second optical signal to be transmitted to the user terminal, and transmit the multiplexed signals to the side of the user terminal; and   branching unit installed at such a degree of distance from the wavelength division multiplexing unit as to make ignorable cross-talk influence of the first optical signal upon the second optical signal in the multiplexed optical signals, branches the optical signals transmitted from the wavelength division multiplexing unit into a plurality of optical transmission paths, and transmits the branched optical signals to the sides of the user terminals.   
     
     
         4 . An optical transmission method comprising:
 first branching unit branches first optical signals to be transmitted to user terminals into a plurality of wavelength division multiplexing unit and thus transmit the branched optical signals thereto;   second branching unit branches second optical signals to be transmitted to the user terminals into the plurality of wavelength division multiplexing unit and thus transmit the branched optical signals thereto; and   the wavelength division multiplexing unit multiplexes, by wavelength division multiplexing, the optical signals transmitted from the first branching unit and from the second branching unit, and thus transmit the multiplexed optical signals to the sides of the user terminal.