Physical Layer Security Based On Cooperative Jamming In Wireless Network

With the development of the wireless network,people become more related to the world and the Internet.The privacy of themselves and the messages they sent has came into an equally serious position.While the encryption methods suffer from quantum calculation and large memory space requirement,the physical layer(PHY)security becomes one of hot-spot solutions.From the single-input single-output(SISO)systems to the multi-input multiple-output(MIMO)systems,the research direction has undergone a shallow to deep process in PHY security.The assumptions and models are much closer to the real world situation than decades ago.However,when we have abounded papers contributed to the PHY security in MIMO system,in MIMO-OFDM,there is still lacking of related work in PHY security,especially in eavesdropper preventing.OFDM has good resistance to frequency fading,which gives MIMO a more stable channel.But OFDM is also vulnerable to attackers who intend to interrupt the communication system.Hence,researchers are engaged in preventing the system from the interruptions and pay no attention to the eavesdroppers at the same time.It has not been proved that the OFDM system is robust enough to eavesdroppers.Also,the preventing schemes work in MIMO cannot be applied to MIMO-OFDM due to the OFDM feature.Therefore,the blank of the eavesdropper preventing research needs to be filled with a new anti-eavesdropping scheme.Based on the above premise,this paper propose two anti-eavesdropping schemes based on MIMO-OFDM environment.In Chapter 3,we present a self-cooperative anti-eavesdropping program.The ideal secrecy capacity can be achieved by antenna allocation among and within sub-carriers besides convex optimization.At the same time,in order to evaluate the characteristics of MIMO and OFDM networks at the same time,a new evaluation standard is proposed.In Chapter 4,we propose a cooperative anti-eavesdropping scheme.Antenna allocation is designed to handle both the unknown known eavesdropper's CSI situations.In the case of unknown eavesdropper's CSI,through a new double-check mechanism we can exclude the eavesdropper from the helpers.Finally,the genetic algorithm is used to gain the sub-optimization solution of the secrecy capacity.The evaluation results of the two schemes are given separately in Chapter 3 and Chapter 4.The results show the efficiency of the schemes.In the last Chapter,we conclude the whole article and make a prospection of the future research.