Patent ID: 7689124

Claim:
An OCDMA system including a base station connected to a plurality of user terminals, comprising: an encoder in each user terminal including: time domain encoding means for creating a time domain code having a sequence according to inputted data bits or a complementary code which is complementary to the time domain code; optical modulation means for selectively outputting lights, in which the lights are incident upon the optical modulation means from the outside, to two output leads, respectively, according to a chip bit of the time domain code or the complementary code; and wavelength domain encoding means for generating a two-dimensional code by encoding the light outputted from the first output lead of the optical modulation means into a wavelength domain sequence and the complementary two-dimensional code which is complementary to the two-dimensional code by encoding the light outputted from the second output lead of the optical modulation means into a complementary sequence of the wavelength domain sequence, and transmitting the two-dimensional code and the complementary two-dimensional code to the base station; and a decoder in each user terminal including: wavelength decoding means for receiving an optical signal code encoded by the encoder from the base station, and decoding the optical signal code in wavelength domain to output an electric signal thereto; time domain decoding means for decoding the electric signal in time domain; and threshold determination means for determining whether the decoded signal in the time domain decoding means is a threshold, and outputting data bits based on the determination, wherein the two-dimensional code is a matrix type code generated from two different PN sequences including a time domain PN sequence in a first dimension and a wavelength domain PN sequence in a second dimension.