The Analysis,Optimization And Encryption Of Physical Layer Security For Visible Light Communication

Visible light communication(VLC)is an important complementary technology to cope with the spectrum scarcity problem of existing wireless communication with the aid of rich and license-free visible spectrum resource and high space reuse.Moreover,compared to the traditional radio frequency(RF)communication,VLC provide a better security due to the VLC happened in the line-of-sight(LoS)range in most case.However,the VLC channel is still of broadcast nature.That makes VLC links inherently susceptible to eavesdropping by unintended or unauthorized users in these public areas.Thus,it is very important to enhance the VLC systems secure.Unlike the RF systems that conventionally modelled as an average power constraint,the practical VLC systems modelled as both average power constraint and amplitude constraints.Thus,the strategy for RF physical layer security cannot be directly used in VLC system.In this paper,based on the closed-form lower and upper bounds on the capacity of amplitude-constrained VLC systems,the security performance of VLC physical layer is studied,and the robust beamforming optimization is designed.Moreover,based on the true random number,the encryption mode for VLC systems by the cryptography is proposed.The novelty and contributions in this paper are highlighted as follows.(1)Performance analysis for SOP and ASC under amplitude constraintConsidering an indoor VLC downlink scenario with one legitimate user and a group eavesdroppers,and the location of the legitimate user and the eavesdroppers is modeled as uniform distribution and poisson point process(PPP),respectively.Then,the signal noise ratio(SNR)of the legitimate user and the eavesdroppers are derived by the random distribution position model.Meantime,for the unique amplitude constraint for the VLC systems and the average power constraint inherent for the wireless communication systems,the multiple upper and lower expressions of the instantaneous channel capacity of VLC are simulated and compared,and an appropriate upper and lower expression was selected,respectively.Moreover,the secrecy outage probability(SOP)and average secrecy capacity(ASC)closed analytical expressions of upper and lower bound are derived based on the statistical characteristics of SNR and the upper and lower limits of VLC channel capacity.Furthermore,the theoretical analysis is verified by the Monte-Carlo simulation which based on Matlab,and some insightful and meaningful performance analysis of SOP and ASC are conducted.In addition,the above mentioned work provides theoretical guide for the robust beamforming optimization for the multi-input single-output(MISO)-VLC system.(2)The robust beamforming optimization for indoor MISO VLC systemsThe problem of robust safety beamforming in indoor MISO visible light communication system under incomplete channel state information(CSI)is studied.In this paper,under the probabilistic CSI error model,the complex-cycle Gaussian model is used to characterize the uncertainty of channel CSI,and then the Bernstein-type inequality is used and the slack variables is introduced to solve the non-convex problem.The convexity problem is transformed into convex problem,and the numerical simulation results are used to verify the effectiveness and robustness of the proposed method.The results show that under the probabilistic CSI error model,a suboptimal beamforming scheme is found to complete the VLC physical layer security optimization design.(3)The key encryption design under based on ultra-fast true random numberA VLC physical layer key encryption mode based on ultra-fast true random source is designed.This paper starts with information security theory and cryptography,and combines VLC channel characteristics to propose a VLC physical layer encryption mode based on one-time password book.In the implementation phase,an ultra-fast random source based on Field-Programmable Gate Array(FPGA)and Boolean network technology is designed to generate a one-time codebook.And a VLC physical layer encryption scheme based on frame structure of the IEEE 802.15.7 standard is proposed.Finally,the complete process of VLC physical layer key encryption is designed,and the VLC physical layer encryption is realized,furthermore,the secure of VLC systems is improved.