Performance Analysis of 1D and 2D in Optical Code Division Multiple Access

Optical code division multiple access system (OCDMA) achievements the advantages of CDMA and Optical communication. Optical code-division multiple-access is proposed as a natural solution to achieving asynchronous, high-speed connectivity in a local area network environment. Optical CDMA is shown to be competitive with other networking technologies such as WDMA and TDMA, but has the benefit of more flexibility, simpler protocols, and no need for centralized network control. OCDMA encoding/decoding process provides a high level of security which is directly implemented in the physical layer. In OCDMA, type of coding technique plays a major factor that influencing its performance. This paper presents performance analysis of two important OCDMA coding techniques namely - 1-D and 2-D codes. Firstly performance analysis of various 1-D codes namely Walsh Hadamard codes (WHC), Optical orthogonal codes (OOC) and Zero cross correlation (ZCC) has been carried out. Secondly performance analysis of 2-D Wavelength/Time (W/T) codes has been carried out. The performance metrics on which the various codes performance has been measured are: different data formats (NR and RZ), increasing fiber distance, amount of received power, increasing the bit rate and number of simultaneous active user. Simulated results show that among 1-D codes ZCC codes provides the best overall performance over OOC and WHC. 1-D codes provide low bit error rate (BER) but they possess high temporal length. To overcome this, 2-D codes have been used which have higher cardinality than 1-D code.