OCDMA SYSTEM: NEW DETECTION SCHEME AND ENCODER-DECODER STRUCTURE BASED ON FIBRE BRAGG GRATINGS (FBGs) FOR VCC CODE

摘要

The success of complementary detection scheme to reduce the multiuser interference (MUI) in spectral amplitude coding optical code division multiple access (SAC-OCDMA) has motivated the communication community to propose many codes with ideal in-phase cross correlation (CC). However, the complementary detection scheme can successfully reproduce desired signals for code sequences which have fixed CC. In this paper, a new detection scheme namely XOR subtraction scheme is proposed. This new detection scheme can be used even if the CC is not fixed. In addition, a new encoder/decoder structure based on this new technique using fibre Bragg gratings (FBGs) for vector combinatorial code (VCC) is proposed. The performance of the system was characterized by referring to signal to noise ratio (SNR), bit error rate (BER), and Psr. The study also shows that high performance of XOR detection scheme can be achieved even when the number of users is high, while maintaining a good SNR and low BER (10~(-14)).