Performance Evaluation of Correlation Properties of Quasi Orthogonal Prime Codes for Optical CDMA Communication

Optical code division multiple access (OCDMA) is one of the promising technologies to be implemented using all-optical networks. The performance of OCDMA system is largely dependent on the particular codes used for encoding. A proper choice of code family as well as code dimension is of prime importance due to various transmitter and receiver design considerations. This paper mainly aims at evaluation of desirable characteristics of various spreading codes based on the prime sequences. An extensive effort has been done in this paper to evaluate the correlation characteristics of various types of one-dimensional (1-D), 2-D and 3-D prime codes for OCDMA communication system. The detailed mathematical modelling has also been explained. It is observed that an addition in coding dimension leads to significant improvement in the code characteristics.

A New Prime Code for Synchronous Optical Code Division Multiple-Access Networks

A new spreading code based on a prime code for synchronous optical code-division multiple-access networks that can be used in monitoring applications has been proposed. The new code is referred to as “extended grouped new modified prime code.” This new code has the ability to support more terminal devices than other prime codes. In addition, it patches subsequences with “0s” leading to lower power consumption. The proposed code has an improved cross-correlation resulting in enhanced BER performance. The code construction and parameters are provided. The operating performance, using incoherent on-off keying modulation and incoherent pulse position modulation systems, has been analyzed. The performance of the code was compared with other prime codes. The results demonstrate an improved performance, and a BER floor of 10−9 was achieved.