Trade off between a proposed FSK and PPM schemes for MAI cancellation in OCDMA systems

The current paper, proposes a simple and efficient multiple access interference (MAI) cancellation scheme in optical code division multiple access (OCDMA) system. The proposed scheme is based on hybrid frequency shift keying (FSK) with adopting an efficient spreading sequence code. Coherent FSK modulation a long with incoherent demodulation using arrayed-wave guide grating has been examined in the transceiver structure. In the proposed technique, a reference signal is constructed by using one of the addressed spreading sequences and MAI cancellation is performed by subtracting the reference signal from the received signal of the desired user. The performance of the proposed FSK-OCDMA system is compared with the performance of the existence Pulse Position Modulation (PPM)´OCDMA system. The simulated computer results reveal that the performance of the proposed technique is superior to the performance of the PPM technique in terms of lower bit error rate (BER) and higher bit-rate under the same conditions. Also, the results indicate that the proposed scheme is very power efficient and when the bit-rate is constant; its network capacity can be expanded to accommodate great number of simultaneous active users with low error-rate. Moreover, the proposed scheme could simplify the hardware of the receiver design.