Optimal code design for multi wavelength OOC optical CDMA systems
Résumé
The objective of this work is to design optimal codes for a 2 Dimensional Optical Code Division Multiple Access system (2D-OCDMA), and to test their robustness to noise perturbation. 2D coding is performed by Multi-Wavelength Optical Orthogonal Codes (MWOOC). They are obtained with our new construction method which permits to choose the code parameters with high flexibility. Different receiver structures are studied: a Conventional Correlation Receiver (CCR), and a Parallel Interference Cancellation receiver (PIC). For each structure, the optimal code parameters are evaluated, in order to obtain a Bit Error Rate (BER) 10-9, for 30 active users, with a minimal temporal code length, and a minimal number of wavelengths. Finally, we show that, compared to the CCR, the PIC receiver permits to reduce the temporal code length and the number of wavelength, and that it also permits to reduce the required SNR for noisy signal.