Research On Physical Layer Security For Full-duplex Wireless Energy Harvesting

The lack of spectrum resource,limited energy and security threat are the challenges impeding the development of the new generation of wireless communication.This thesis conducts in-depth research on the physical layer security of the full-duplex wireless energy harvesting system.The system considers two full-duplex source nodes to perform bidirectional communication in cooperation with amplify and forward full-duplex multi-antenna relay.The relay node uses wireless energy harvesting technology obtains the energy required for its own data transmission.There is also an eavesdropping node in the system to eavesdrop on the source node and the relay node.The main research work of this thesis includes the following two aspects:First,for the scenario where the channel state information of all channels in the above system model is known and ideal,a safe transmission strategy based on beamforming vector optimization design is proposed.This strategy aims at two energy harvesting protocols,power splitting and time splitting.Under the constraint of relay node transmit power and zero-forcing constraint,we design the relay node's transmit beamforming vector to maximize the system's sum secrecy rate.For this non-convex optimization problem,difference of convex programming is used to transform the non-convex optimization problem into a linear convex problem for iterative solution.The simulation proves that the proposed algorithm can quickly converge,and compared with the traditional arbitrary beamforming design scheme,the proposed scheme can obtain higher sum security rate under different system parameters.Secondly,for the scenario where the channel state information of the eavesdropping channel in the above system model is not ideal,but other channel state information is known and ideal,a safe transmission strategy based on joint optimization of beamforming vector and time splitting factor is proposed.This strategy maximizes the primary link sum rate by jointly optimizing the beamforming vector and the time splitting factor under the constraints of the relay node's limited energy harvesting,maximum eavesdropping rate constraint and zero-forcing constraint.For this non-convex optimization problem,an alternating optimization algorithm based on semi-definite programming and one-dimensional search is used to solve the optimization problem.The effects of different system parameters on the system sum rate is analyzed through simulation,and compared with the sum rate obtained when the eavesdropping channel status information is ideal.The results show that the sum rate obtained by the two is not much different,which proves that the proposed algorithm has a good robustness.In conclusion,the safety transmission strategy based on beamforming vector and split factor optimization proposed in this thesis provides technical support for the application of full-duplex in wireless energy-harvesting system.