| Popis: |
The major interference factor in Optical Code Multiple Access (OCDMA) is to overcome the Multiple Access Interference (MAI) noises, which induce the occurrence of Bit Error Rate (BER). The Phase Induced Intensity Noise (PIIN) is the dominant noise in the receiver, which is closely related to the MAI. In this paper, we focus on two different detection technologies Direct-detection and AND-Subtract detection. The study depends on simulation modeling and the code properties; 2-D MDW code is used in this investigation because of the unity cross-correlation. The weights of the code are k1=4,k2=2, the first represented the spectral weight, second represent the temporal weight. OptiSystem software (Version 11.0) has been used to study the performance of the code with this two detection for four users. The BER was measured against different data rate and transmission distance over direct detection as well as AND-Subtraction detection. The 2-D MDW code shows a high performance when implemented with direct detection with high bit rate reach 2.5 Gbps even in short distance 12 Km, but, for 622 Mbps data rate the transmission range reach 60 km. And for received power, the code can gain BER = 10-9 at -25 dBm with 622 Mbps and -20 dBm at 1.25 Gbps. |
