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Research On The Physical Layer Security In Non-Orthogonal Multiple Access Systems

Posted on:2023-10-17Degree:DoctorType:Dissertation
Country:ChinaCandidate:C Y YuanFull Text:PDF
GTID:1528306914476494Subject:Information and Communication Engineering
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With the rapid development of wireless communication and the continuous emergence of state-of-the-art wireless networks(e.g.,Internet of Things,Internet of Vehicles,Machine-to-machine communication networks,etc.),a large amount of sensitive and confidential information is transmitted through wireless channels,and transmission security faces serious challenges.As a crucial supplement to traditional cryptographic schemes,Physical-Layer Security(PLS)can guarantee security with low computational complexity and has critical theoretical significance for enhancing the secrecy performance of wireless communication.On the other hand,Non-Orthogonal Multiple Access(NOMA),as a pivotal technology to improve spectrum efficiency,has become a research hotspot on wireless communication to address the explosive growth of data traffic and massive mobile device access.Information leakage introduced by co-channel interference in the NOMA system is of importance.Considering the limited resources,how to select suitable secure transmission technologies in specific scenarios is a crucial problem to tackle.From the perspective of PLS transmission,this dissertation investigates how to improve the performance of PLS by exploiting power allocation,carrier matching,beamforming,and cooperative jamming in several typical NOMA scenarios,namely multi-carrier NOMA,multi-user NOMA,multi-antenna NOMA,and cooperative NOMA.Our contributions are summarized as follows.(1)Research on power allocation and performance analysis for secure transmission in multi-carrier NOMA network with a single antenna.Considering the constraints of minimal transmission rate and maximal transmission power of the base station,we build two optimization models of power allocation for the two-user multi-carrier NOMA network with a single antenna to minimize transmission rate and maximize secrecy rate,respectively.Using Karush-Kuhn-Tucker(KKT)condition,we derive the semi-closed-form solution for power allocation.Moreover,we propose an optimization strategy of power allocation based on the block coordinate descent approach,of which we analyze the convergence and computational complexity.Experimental results show that our proposed method can achieve a faster convergence rate than the difference of convex programming-based NOMA.Moreover,our proposed algorithm enjoys lower transmission power or higher secrecy rate than orthogonal multiple access.(2)Research on power allocation and subcarrier matching for secure transmission in multi-user multi-carrier NOMA network.We build a joint optimization model of subcarrier matching and power allocation for the multi-user multi-carrier NOMA network with a single antenna,considering the constraints of minimal transmission rate,the limited number of users per subcarrier,and the maximal transmission power of the base station to achieve the maximal secrecy rate.We select the matching theory to convert the user-carrier pairing problem into two-sided pairing between users and carriers.We also propose a carrier matching strategy based on the Gale-Shapley Algorithm.Moreover,according to the feasible transmission power and the monotonicity of objective function based on users’ quality of service requirement,we adopt the KKT condition to obtain the closed-form solution of optimal power allocation.Simulation results show that our proposed approach can improve 115.8%secure transmission compared with orthogonal multiple access.(3)Research on power allocation and beamforming for secure transmission in multi-antenna multi-user NOMA network.For the multi-antenna multicarrier NOMA network with two users,considering the constraints of the limited transmission rate of users and maximal transmission power of the base station,we build a joint optimization model of power allocation and beamforming to maximize the secrecy rate.We derive the necessary conditions of the global optimal power allocation and obtain the semi-closed-form power allocation solution.Block coordinate descent is utilized to decompose the original problem into subproblems in each carrier.Moreover,we convert the nonconvex problem into a convex formulation based on Dinkelbach’s approach,successive convex approximation,and positive semi-definite relaxation.Experimental results show that the secrecy rate of our proposed strategy is 78.2%higher than orthogonal multiple access.(4)Research on performance analysis of secure transmission and power allocation in cooperative NOMA network.We derive the closed-form expression and asymptotic approximation of the ergodic secrecy rate through probability theory for the cooperative relaying-based NOMA network.We propose a secrecy strategy based on cooperative jamming of the source node in the NOMA network to achieve higher secrecy performance.With the help of optimization theory,a power allocation strategy is used to achieve the maximal ergodic secrecy rate,and we derive the optimal power allocation.Simulation results verify our theoretical analysis.The proposed scheme achieves a 78.1%higher secrecy rate than non-jamming NOMA.
Keywords/Search Tags:Physical layer security, Non-orthogonal multiple access, Secrecy rate, Cooperative jamming, Resource allocation
PDF Full Text Request
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