Research On Secure Transmission Technology Of Spatial Modulation Network

Spatial modulation(SM)is emerged as a green,low-cost and high energy-efficiency communication technique.SM is equipped with a few number of radio frequency chains,which is the third way between space-time code and bell labs layered space-time.SM uses both the amplitude phase modulation symbols and the index of activated antenna to transmit bit information,which greatly reduces costs and increase energy efficiency.Since the broadcast nature of wireless communications,the communication between the transmitter and the legitimate receiver is vulnerable to the hostile user.As a result,how to achieve a secure transmission for SM systems becomes a challenging problem.In the context,this thesis focuses on the security of SM system,and introduces artificial noise(AN)signals into the transmitted SM signals to interfere with eavesdroppers.Our main contributions are as follows.(1)The signal transmitted by secure SM systems consists of the confidential message(CM)and AN.How to allocate the power of the CM and AN is crucial,so this thesis devises two power allocation(PA)strategies: maximizing the approximate secrecy rate based on gradient ascent(Max-ASR-GA)and maximizing the product of signal-to-interference-plus-noise ratio and AN-to-signal-plus-noise ratio(Max-P-SINR-ANSNR).For Max-P-SINR-ANSNR,we present its closed-form solution and thereby greatly reduce its computational complexity.Simulation results show that the two proposed PA methods approach the optimal PA method using exhaustive search method in terms of the secrecy rate(SR)performance.Notably,the SR performance of the proposed schemes are far superior to that of conventional PA methods,and strikes a good balance between the SR performance and the computational complexity.(2)In this thesis,we make an investigation of several key technologies in hybrid secure SM system: hybrid precoding and transmit antenna sub-array selection(TASAS).To reduce the computational complexity,a closed-form approximate secrecy rate expression is derived as a new objective function.The Max-ASR-GA method,as well as maximizing the approximate secrecy rate alternating direction method of multipliers(Max-ASR-ADMM)hybrid precoding algorithm is proposed.Additionally,to further improving the security,both the methods of maximizing the eigenvalue(Max-EV)and maximizing the approximate secrecy rate(Max-ASR)of TASAS are proposed.In fact,the Max-P-SINR-ANSNR method is generalized to the case of hybrid SM.Simulation results show that the proposed Max-ASR-GA and Max-ASR-ADMM harvest significant SR performance gains over the existing hybrid precoding algorithms.Among them,the SR performance of the Max-ASR-GA algorithm is slightly higher than the Max-ASR-ADMM algorithm.Moreover,the proposed three TASAS methods also have a good SR performance.The SR performance of these methods has the following decreasing order:Max-ASR,Max-EV,and Max-P-SINR-ANSNR.Interestingly,the proposed Max-EV method obtains an extremely low complexity at the risk of a little SR performance loss.