Security enhancement in optical code division multiple access network

Abstract

Optical code division multiple access (OCDMA) technology has become a promising technology to implement all-optical communication for transporting high-volume, high-quality multipurpose information reliably with fully asynchronous access and simplified decentralized network control. Due to its coded nature OCDMA is considered to be relatively secure as compared to other optical networks, but a deeper study of OCDMA has revealed that it is easy to intercept and jam the data. Hence, the photonic layer security has become a crucial issue in OCDMA networks. The physical layer of the network can be attacked by an eavesdropper to intercept the data and by the jammer to disrupt communication. Therefore, the main focus of this thesis is to increase optical layer security in OCDMA network by providing data confidentiality against eavesdropping and signal availability against jamming. Firstly, the security issue of confidentiality enhancement against eavesdropping in an OCDMA network is addressed. An eavesdropper can effortlessly intercept the transmitted data whenever he gets isolated user s signal access. Hence, eavesdropper s code interception performance for single transmitting user in OCDMA network is evaluated first. A novel technique called virtual user scheme is proposed to increase the security against the unauthorized access. It is shown that the information is successfully transmitted without compromising its confidentiality with the proposed scheme. Secondly, security concern of signal availability against jamming in an OCDMA network is taken into account. A high power jammer can easily disrupt the OCDMA transmission by transmitting at the same waveband as of the authorized user. Therefore, a novel anti-jamming technique using wavelength conversion principle is proposed to mitigate the effect of jammer. An OCDMA network is simulated with proposed wavelength converter and it is shown that data can be securely transmitted even in the presence of high power jammer.