Research On The Security Transmission Strategy Of The Physical Layer Security Of The MIMO PLC System With Relay

As broadband power line communication(PLC)plays an increasingly important role in smart grids,traditional communication security algorithms and current communication quality can no longer satisfy current demand.In view of the fact that traditional security algorithms cannot essentially solve the PLC security problem,new research strategy based on physical layer security have emerged,and it is expected that the PLC security problem can be solved from the essence.However,there are few research results related to the physical layer security of the MIMO PLC system with relay.Therefore,this thesis conducts the following research on the physical layer security of the MIMO PLC system with relay:(1)The channel model and wiretap model of the MIMO PLC system are built.Firstly,the principles and characteristics of the physical layer security are analyzed,and the noise characteristics,multipath characteristics,and frequency selection characteristics of the power line channel are analyzed.Secondly,the power line Lognormal channel model and the MK(Manfred Zimmermann and Klaus Dostert)channel model are studied,and power line noise model is built;Thirdly,the MIMO eavesdropping model is analyzed and built.(2)For the multi-user MIMO PLC system with relay,a physical layer security scheme based on the distributed iterative solution algorithm is proposed to minimize MSE(Mean Square Error).Firstly,the scheme proposes to minimize the MSE of legal communication pairs and keep the MSE of eavesdroppers above the desired threshold.Secondly,in the presence of inter-channel interference,power constraints,and imperfect channel state information,the signal is encoded and decoded by joint design of the transmit precoding matrix,the relay forwarding matrix,and the receive filter matrix.Finally,to overcome this non-convex optimization,a distributed iterative algorithm is proposed.The non-convex optimization problem is decomposed into three convex optimization sub-problems,and the transmit precoding matrix,the relay forwarding matrix,and the receive filter matrix can be solved by the algorithm.(3)For the full-duplex MIMO PLC system with relay,a physical layer security coding scheme based on artificial noise assistance is proposed.Firstly,it utilizes the multi-channel characteristics of the relay,then uses some channels to transmit private data and other channels to transmit artificial noise.The artificial noise is in the null space of the legal receiving nodes and artificial noise will interfere the eavesdropping ability as much as possible.Secondly,under the case of power constraints,full-duplex self-interference signals and unknown interference sources,the relay utilizes the acquired channel state information to design a private data encoding matrix and artificial noise covariance matrix.And establish an optimization problem with the security rate as the performance of physical layer security.Finally,for the non-convex optimization problem,a distributed iterative solution algorithm based on block gradient descent is proposed.The non-convex optimization problem is transformed into a series of convex optimization sub-problems.the private data encoding matrix and artificial noise coordination matrix are solved by the iterative algorithm.The simulation experiment results show that the MIMO PLC system with relay can achieve better secure communication.The security performances of MIMO PLC system are ensured,and the effectiveness of the algorithms is verified.The algorithms proposed in this thesis can be applied to applications and services in PLC system,and can ensure the security of data transmission in these applications and services.Therefore,in the future,broadband power line communications will play an increasingly important role in the applications and services of smart grids.