BER Performance of Spectral / Spatial OCDMA for UWO Link Using Perfect Difference Code

In this paper, the performance of spectral/spatial optical code division multiple access (2D-OCDMA) system through underwater wireless optical (UWO) medium is evaluated where 2D perfect difference codes are used as user code address. In the proposed system, a LED of 532nm wavelength is considered as optical source whereas p-i-n photodiode is employed as optical detector. PIIN, thermal noises and shot noises are taken into consideration while calculating the bit error rate (BER) of the system. The performance of the proposed system is analyzed for various types water medium (i.e., pure sea water, clear ocean water and coastal ocean water). The BER performance is ascertained as a function of transmitter power, link distance, data rate and received power through water medium. It is found that the system BER performance significantly depends on the water types. The best system performance is obtained in pure sea water due to the least amount of impurity where clear ocean water provided better results than coastal ocean water having the highest amount of impurity. From numerical results it is observed that best BER performance can be achieved for lower distance of transmission in pure sea water channel among all water channels. The system BER performance degraded with increasing the link distance while increased transmitted optical power improves the system performance.