The Optimization Research For The Cooperation Jamming In Wireless Communication Network

In the wireless communication network, because of the openness of the wireless channel, the signals are vulnerable to eavesdrop during the communication process, which brings serious challenges on the security performance and also has attracted great attentions. And it's significant for people to promote the physical layer security utilizing the cooperative relay. In this thesis, we focus on the problem of cooperation jamming in the wireless network and design the optimization models from the perspective of information theory.First, we consider the one-way wireless communication system where the source node transmits messages with the help of relay nodes in the presence of an eavesdropper. And in this system, the destination node not only acts as the signal receiver but also transmits the artificial noise (AN) as a jammer. Our paper considers the cases that the channel state information (CSI) of the eavesdropper is known and the CSI is unknown respectively. For each cases, we establish the minimize optimization problems for the system power on the condition of guaranteeing the communication quality so that we can calculate the beamforming vector and power allocation. By some formula derivations,the optimization problems can be transformed into the semi-definite programming problems (SDP) and then we can obtain the rank-one solutions. Finally, numerical results are provided the efficiency that destination node transmits the AN as a jammer.Second, we also consider the two-way relay communication system in the presence of an eavesdropper. In this thesis, it's assumed that the CSI of the eavesdropper is not perfect, but the channel estimation error satisfies norm-bounded model. With the available imperfect channel estimates, we propose the robust model for minimizing the signal-to-interference-plus-noise (SINR) of the eavesdropper. By the semi-definite relaxation (SDR), the problem of minimizing the worst case of SINRs can be converted to a SDP and we can find the global optimal solution with the rank-one decomposition theorem. Then, for the communication security, we formulate an optimization model which minimizes the total relay power consumption subject to the SINRs receivable by the intended source nodes above some thresholds and the worst case SINRs of the eavesdropper below others, and then we can relax the problem into a SDP in the same way and find the rank-one solution of the SDP. Finally, Numerical results are provided to show the effectiveness and superiority of the proposed algorithms.Finally, we discuss the weaknesses of the models and algorithms in this thesis and point out some further prospect.