ABSTRACT
Optical CDMA transmission systems can not only increase system capacity, but also achieve physical-layer security against fiber tapping attacks. In this paper, we examine the information-theoretic security of optical CDMA systems by evaluating the trade off between the achieved information capacity and the confidentiality. In particular, we established a wiretap channel model of optical CDMA systems, based on which we have evaluated the impacts of key system parameters, such as the type of code words, the number of users M, the code lengths N and the input optical power P, on the system security. Our results indicate that key system parameters play an important role and choosing suitable values of these system parameters will be helpful to improve the secure performance of optical CDMA systems to some degree. For example, choosing the code words whose cross-correlation λ values are smaller, increasing the code lengths N or the input optical power P and reducing the number of users M properly can all be used to improve the secure performance of optical CDMA systems.
