Asynchronous hybrid optical code division/wavelength division multiple access system

We analyze the asynchronous operation for the hybrid OCDMA/WDMA system. The OCDMA techniques can be implemented directly in the optical domain based on ultrashort optical pulse laser sources and the asynchronous operation of OCDMA systems is a very desirable characteristic of any multiplexing technique especially at high data rates. For the performance analysis of the hybrid OCDMA/WDMA system, we calculated the bit error rate (BER) and capacity and compared both situations of synchronous and asynchronous transmission. Further, the system performance improves drastically by increasing the code length (M) and more users with asynchronous multiplexed communications can be provided. As the ratio (D) between OCDMA user's bit duration and WDMA user's bit duration becomes larger, the BER becomes smaller. If the OCDMA data rate is fixed, then when D becomes larger or, equivalently, WDMA date rate becomes larger, the total throughput improves drastically. But, if the WDMA data rate is fixed, then when D becomes larger or, equivalently, OCDMA date rate becomes smaller, the total throughput becomes smaller. Therefore, there will be a trade-off between D and the total throughput.