An OCDMA Scheme to Reduce Multiple Access Interference and Enhance Performance for Optical Subscriber Access Networks

摘要

We propose a new optical code division multiple access(OCDMA) scheme for reducing multiple accessinterference (MAI) and enhancing performance foroptical subscriber access networks using modifiedpseudorandom noise (PN)-coded fiber Bragg gratingswith bipolar OCDMA decoders. Through the bipolarOCDMA decoder and the modified PN codes, MAIamong users is effectively depressed. As the data areencoded either by a unipolar signature sequence of themodified PN code or its complement according to whetherthe data bit is 1 or 0, the bit error ratio (BER) can be moreimproved with the same signal to interference plus noiseratio over the conventional on-off shift keying-basedOCDMA system. We prove by numerical analysis that theBER of the proposed bipolar OCDMA system is betterthan the conventional unipolar OCDMA system. We alsoanalyze the spectral power distortion effects of thebroadband light source.