Physical layer security performance study for wireless networks with cooperative jamming
Due to the rapid development of wireless communication technology and widespread proliferation of wireless user equipment, wireless networks become indispensable for lots of applications in daily life. The broadcast nature of wireless medium makes information exchange in such networks vulnerable to eavesdropping attacks from malicious eavesdroppers, resulting in network security one of the major concerns for system designers. Physical layer (PHY) security has been proposed as one promising
... ology to provide security guarantee for wireless communications, owing to its unique advantages over traditional cryptography-based mechanisms, like an everlasting security guarantee and no need for costly secret key distribution/management and complex encryption algorithms. This thesis therefore focuses on the PHY security performance study for wireless networks with cooperative jamming (a typical PHY security technique), where non-transmitting helper nodes generate jamming signals to counteract eavesdropping attacks. We first explore the PHY security performances of small-scale wireless networks with non-colluding (i.e., independently-operating) eavesdroppers, for which we study iii the eavesdropper-tolerance capability (ETC) of a two-hop wireless network with one source-destination pair, multiple relays and multiple non-colluding eavesdroppers. We consider two relay selection schemes to forward the packets from the source to the destination, i.e., random relaying and opportunistic relaying. For both relaying schemes, we first derive the secrecy outage probability (SOP) and transmission outage probability (TOP) of the network by applying the classical Probability Theory. We then determine the ETC of the network by solving an optimization problem that aims to maximize the number of eavesdroppers that can be tolerated under a certain SOP constraint and a certain TOP constraint. Finally, we present extensive simulation and numerical results to demonstrate the validity of the theoretical analysis and also to illustrate our theoretical findings. We then investigate the PHY security performances of small-scale wireless networks with colluding (i.e., cooperatively-operating) eavesdroppers, for which we study the SOP performance of a two-hop wireless network with one source-destination pair, multiple relays and multiple colluding eavesdroppers. Based on the classical Probability Theory, we first conduct analysis on the SOP of the simple non-colluding case. For the SOP analysis of the more hazardous M-colluding scenario, where any M eavesdroppers can combine their observations to decode the message, the techniques of Laplace transform, keyhole contour integral, and Cauchy Integral Theorem are jointly adopted to work around the highly cumbersome multifold convolution problem involved in such analysis, such that the related signal-to-interference ratio modeling for all colluding eavesdroppers can be conducted and thus the corresponding SOP can be analytically determined. Finally, simulation and numerical results are provided to demonstrate the validity of the theoretical analysis also to illustrate our theoretical findings. Finally, we examine the cooperative jamming design issue in large-scale wireless networks. Towards this end, we propose a friendship-based cooperative jamming iv scheme to ensure secure communications in a finite Poisson network with one sourcedestination pair, multiple legitimate nodes and multiple eavesdroppers distributed according to two independent and homogeneous Poisson Point Processes (PPP), respectively. The jamming scheme consists of a Local Friendship Circle (LFC) and a Long-range Friendship Annulus (LFA), where all legitimate nodes in the LFC serve as jammers, but the legitimate nodes in the LFA are selected as jammers through three location-based policies. To understand both the security and reliability performances of the proposed jamming scheme, we first model the sum interference at any location in the network by deriving its Laplace transform under two typical path loss scenarios. With the help of the interference Laplace transform results, we then derive the exact expression for the TOP and determine both the upper and lower bounds on the SOP, such that the overall outage performances of the proposed jamming scheme can be depicted. Finally, we present extensive numerical results to validate the theoretical analysis of TOP and SOP and also to illustrate the impacts of the friendship-based cooperative jamming on the network performances. v I would also like to give my sincere gratitude to Professor Yulong Shen of Xidian University, China, who gave me the opportunity to work together with Professor Xiaohong Jiang and other members in the laboratory when I was a Master student. He opened the door of scientific research for me and showed me the way to be an excellent researcher.