SECRECY CAPACITY ANALYSIS OVER COMPOSITE WEIBULL-LOGNORMAL CHANNEL

Abstract

With increase in use of wireless communication, there is an urgent need for security and privacy to achieve secure communication. Generally, cryptographic techniques ignore the physical nature of the wireless medium i.e it is assumed that the channel is error free. Since we know that the wireless channel suffers from various distortions which may depend upon various internal and external factors. Thus fading, which is physical to wireless medium should be taken into consideration when hoping to achieve a secure reliable communication. In past, attempts have been made to study the impact of fading on what is called secrecy capacity of the channel. This gives us a clear idea on how the physical nature of medium can play important role in achieving perfect reliable communication link. In [2], secrecy capacity in case of quasi-static rayleigh fading has been considered. In [1], secrecy capacity of k-μ fading is discussed. Probability of SPSC of weibull multipath fading is investigated in [3]. But analysis of composite multipath/shadowing is yet to be discussed. As we know that in real life scenario, fading is caused by both multipath and shadowing. In order to fill this gap in this thesis, we have considered the transmission of confidential information over composite Weibull-lognormal fading channel intended between two legitimate users. An adversary also experiencing Weibull-lognormal composite fading is considered which tries to maliciously eavesdrop the channel. Furthermore we have also obtained closed form expressions in order to calculate secrecy capacity and its lower bound. The versatility of Weibull-lognormal fading channel can be used such that the results derived in this thesis can be used to determine outage probability parameters such as SPSC and SOPL for a number of other fading scenarios such as Rayleigh, Gaussian etc. This thesis also throws light on the fact that fading is not always undesirable. It sometimes (in our case) can be used to successfully transfer secret information.