Suppression of interuser interference for fiber-optic synchronous code division multiple access networks

In this paper, a new coding architecture is proposed for fiber-optic synchronous code division multiple access (S/CDMA) network by using parallel cancellation scheme and bit-stuffed unipolar m-sequence. The well-known maximal length code (m-sequence) with one bit stuffing which is called bit-stuffed unipolar m-sequence in this paper can achieve unique cross-correlation value . Due to the uniqueness of cross-correlation value of unipolar m-sequence, the proposed parallel cancellation scheme can completely suppress the interuser interference in the negligible effects of noise . In the proposed architecture, the correlator employs avalanche photodiode (APD) for photodetection, and the correlator output can be modeled as a Gaussian random process [7-8]. In addition to the suppression of interuser interference, the inevitable effects of APD noise and thermal noise in the process of photodetection are also investigated in this paper.