Research On Physical Layer Security Transmission Technology With Game Theory

Physical-layer-security is a technical means to realize secure transmission on the basis of discrepancy and reciprocity of wireless channel. Traditional physical layer security mainly focuses on the optimal strategy with single subject under a relatively stable scene. When the scene changes or multiple subjects exist, traditional method for physical layer security is ineffective, while Game Theory may solve this problem. Current physical layer security research has three problems as following:(1) Game Theory based physical layer security lacks unified modeling;(2) When jammer exists, current repeater jamming scheme cannot ensure secure transmission;(3) Networks where multiple single-antenna users exist cannot ensure physical layer secure communication because users lack of spatial redundancy. On account of above problems, this paper studies Game Theory based physical layer secure transmission technology, grounding on National Natural Science Fund Project ’Physical Layer Security Research with Equivalent Channel Characteristics of Wireless Communication’.First, it gives the Game Theory model of physical layer security. Then, for the problem that current repeater jamming scheme cannot ensure secure transmission when jammer exists, it puts forward a relaying physical layer security method on the basis of zero-sum Game; for the problem that because of the lack of spatial redundancy, networks where multiple single-antenna users exist cannot ensure physical layer secure communication, this paper proposes physical layer security method of increasing antenna redundancy on the basis of Cooperative Game. The main work of this paper includes:1. Game Theory based physical layer security model is constructed. This paper combines Game Theory with the rational hypothesis and multi-target strategy optimization needs, which appear in physical layer security research, and presents the necessity of Game Theory by the physical layer security. It makes induction of physical layer security research subjects and methods, integrates the impact of strategy on system performance into physical layer security analysis, constructs the function which maps strategy into system performance, and establishes Game Theory based physical layer security model. According to the real extant scene and action patterns of wireless network nodes, physical layer security researches with Game Theory are completely classified.2. On the basis of zero-sum Game, a relaying physical layer security method is proposed. By solving Game Equilibrium conditions, a non-zero secrecy rate is reached under rigorous environment of concurring jamming and eavesdropping, so as to ensure secrecy communication. The scene of confrontation between relay and jammer is modeled as zero-sum game, with system secrecy rate as payoff; strategies of both sides are extracted; all the probable situations produced by the game are analyzed respectively in scenes of strategic game and extensive game, and according secrecy rates are calculated; equilibrium conditions and consequences of the two game scenes are respectively discussed and given, using maximum minimum method and reverse backtracking method in the game. It also briefly analyzes the situation of repeated game by the two sides. It is verified through simulation that equilibrium does exist and the optimal choice of strategy to achieve it.3. Physical layer security method of increasing antenna redundancy on the basis of Cooperative Game is proposed. Virtual multi-antennas are formed by means of distributed cooperation of users, and artificial noise is transmitted using antenna redundancy to resist eavesdropping behavior of Eve. For the reason that centralized processing and control are unavailable, and each user has its own gain and loss, it is necessary to produce cooperative group to ensure physical layer security by means of coalition formation method of cooperative game. The paper discusses two situations of transmitter knowing and unknowing eavesdropping channel information. Functions of cooperative game characteristics are set, taking power limitation and power-secrecy rate limitation respectively as conditions, and finally converge into cooperative group division which is beneficial to secrecy transmission of signals. When cooperative group division is completed, transmitting signals that comprise artificial noise are formulated to ensure the safety of signal transmission, with cooperative group as unit. What simulation result shows is that in situations that eavesdropping channel information is unknown and known, the average secrecy rates of users are respectively increased0.6bps/Hz and1.3bps/Hz than without cooperative group. In the case that eavesdropper can make jamming, the cooperative group division for known eavesdropping channel can be used to model cooperative group and eavesdropper as two sides zero-sum game, and analyzed in the strategic scene. Moreover, it is testified in simulation of the equilibrium solution in the presence of jamming eavesdropper.