The Secure Communication Transmission Design In Multi-Antenna And Multi-Carrier Channel For Physical Layer

Physical layer security has recently been recognized as a novel and attractive alternative approach to establish information-theoretic confidentiality of messages transmitted between the transmitter and the legitimate receiver over the wireless medium.As opposed to traditional and classical encryption schemes,physical layer security enables the secure communications by only taking the advantage of the inherent characteristics of wireless channels,to disturb eavesdropper's reception without relying on the upper-layer.Multiple-antenna and multiple-carrier techniques,which offer the spatial,temporal and frequency degrees of freedom,can most effectively improve the secrecy capacity via simultaneously increasing the quality of the main channel and impairing that of the wiretap channel.Thus,the reasonable transmission design for multiantenna and multi-carrier wiretap channel at physical-layer security are investigated.The main contributions are as follows:(1)The basic concepts of physical layer security are introduced,and the key points involved in communication transmission design are summarized.Meanwhile,a detailed study about present research status of physical-layer security for multi-antenna,multicarrier,and hybrid multi-carrier and multi-carrier wiretap channels are made.(2)The secrecy rate maximization for multiple-input-multiple-output(MIMO)wiretap channels in the presence of a multiple-antenna eavesdropper are considered.An efficient algorithm based on minorization-maximization(MM)technique is proposed.The proposed algorithm employs a linear function to minorize the objective function and has a closed-form solution at every iteration.In addition,we prove that the proposed algorithm has guaranteed convergence of the sequence of objective values.Moreover,an acceleration scheme,called squared iterative method(SQUAREM),is used to enhance the convergence rate of the proposed algorithm.Then,the proposed algorithm to handle the transmission power minimization problem is extended.Results show that the proposed algorithm have the same secrecy rate performance as the state-of-art algorithm but is much more computationally efficient.(3)The synthesis of discrete finite-alphabet inputs for secure communications in multiple-input-single-output(MISO)wiretap channels are considered.We aim at that the source with the synthesized transmissions can communicate with a legitimate receiver and degrade the performance of a potential eavesdropper.To this end,an optimization problem to minimize the Euclidean distance between the reference inputs and the synthesized inputs is formulated.An iterative algorithm to tackle the non-convex design problem with constant-envelope constraints is devised.Moreover,the proposed methodology is extended to deal with low peak-to-average-power ratio(PAPR)transmissions.Numerical examples demonstrate that the proposed algorithms can achieve the requirement of secrecy communications efficiently.(5)Different secrecy rate optimization problems are considered for a MIMO-OFDM wiretap channel.In particular,a scenario is considered where a communication through a MIMO-OFDM channel is overheard by a multiple-antenna eavesdropper.In this secrecy network,two secrecy rate optimization problems are first investigated: 1)power minimization and 2)secrecy rate maximization.These optimization problems are not convex due to the nonconvex secrecy rate constraint.However,by approximating this secrecy rate constraint based on Taylor series expansion,iterative algorithms are proposed to solve these secrecy rate optimization problems.In addition,the convergence analysis is provided for the proposed algorithms.Due to the efficient issue,an efficient algorithm based on MM technique is proposed.The proposed algorithm employs a linear function to minorize the objective function and has a closed-form solution at every iteration.In addition,we prove that the proposed algorithm has guaranteed convergence of the sequence of objective values.Moreover,an acceleration scheme,called SQUAREM,is used to enhance the convergence rate of the proposed algorithm.Then,the proposed algorithm is extended to handle the transmission power minimization problem.Results show that the proposed algorithm have the same secrecy rate performance as the algorithm based on the Taylor expression but is much more computationally efficient.(6)The design problem of physical layer security communication system based on OFDM is considered.According to the function requirements of system,the frame structure of the physical layer protocol is designed.a design scheme based on OFDM system and the corresponding hardware implementation scheme are proposed.Then,the key software algorithms on the system design are analyzed and discussed.