Performance Analysis of Optical Wireless Communication Systems for Security Enhancement

Abstract

The internet requirement is ever increasing demand and to combat this demand of different internet services such as high-quality multimedia, smart cell phones, online gaming and shopping, cloud computing etc. The optical communication is the heart of networking system which supports high capacity and data rate. In order to meet the exponential growth in internet services and to cope up with the present users, there is immense need of high-capacity wireless networks. There are certain limitations that exist in both short distance and long haul when condition of large capacity needs to be fulfilled. In the past, multiplexing with electrical techniques was used to meet the capacity requirement, but in that case the data rate achieved was lower. Although with incorporation of WDM technique the capacity increased and rate escalated little. Optical code division multiple access (OCDMA) technique has become the prominent technology to support high capacity and multiple transmission of data with complete coding and synchronization. This coded feature of OCDMA technology provides high security level in comparison to the existing techniques. The studies revealed that in case of simple transmission of data with OCDMA technique leads to traffic jam and eavesdropping. Hence, security leakage has become a major concern in these networks. The data is easily interpreted by the eavesdropper and either jammed or modified. Thus, the main motive of this thesis is to increase the security level in IS-OWC networks by making availability of linearly polarised modes and multiplexing methods to avoid eavesdropping. Initially, the issue of cross correlation in IS-OWC networks is addressed. For eliminating cross correlation in IS-OWC system, different existing one-dimensional codes (MD code, Double diagonal weight, random diagonal code and EDW code) are discussed. Further, an enhanced code than the existing ones is presented that also improved bandwidth efficiency. In most of the suggested codes, cross correlation is present either due