5 research outputs found
Joint Optimization for Secure and Reliable Communications in Finite Blocklength Regime
To realize ultra-reliable low latency communications with high spectral
efficiency and security, we investigate a joint optimization problem for
downlink communications with multiple users and eavesdroppers in the finite
blocklength (FBL) regime. We formulate a multi-objective optimization problem
to maximize a sum secrecy rate by developing a secure precoder and to minimize
a maximum error probability and information leakage rate. The main challenges
arise from the complicated multi-objective problem, non-tractable back-off
factors from the FBL assumption, non-convexity and non-smoothness of the
secrecy rate, and the intertwined optimization variables. To address these
challenges, we adopt an alternating optimization approach by decomposing the
problem into two phases: secure precoding design, and maximum error probability
and information leakage rate minimization. In the first phase, we obtain a
lower bound of the secrecy rate and derive a first-order Karush-Kuhn-Tucker
(KKT) condition to identify local optimal solutions with respect to the
precoders. Interpreting the condition as a generalized eigenvalue problem, we
solve the problem by using a power iteration-based method. In the second phase,
we adopt a weighted-sum approach and derive KKT conditions in terms of the
error probabilities and leakage rates for given precoders. Simulations validate
the proposed algorithm.Comment: 30 pages, 8 figure
Secure Precoding for Future Wireless Communication Systems
Department of Electrical EngineeringPhysical layer security has emerged a flourishing strategy to protect confidential information from eavesdroppers with lower computational complexity compared to cryptography. Secure precoding is a promising transmission method of physical layer security to improve security by exploiting an intrinsic attribute of wireless communications. The main goal of the secure precoding is to maximize secrecy rate in multi-input and multi-output (MIMO) systems with the presence of eavesdroppers. Unfortunately, there exists no optimal solution, and also solving the secrecy rate maximization problem becomes more challenging as networks involve a multi-user (MU) and multi-eavesdropper (ME) scenario because of its non-smoothness and non-convexity. In this thesis, I proposed a novel secure precoding algorithm for downlink MU-MIMO systems under ME threat to enhance the secrecy rate, and provide subsequent analyses for realizing ultra-reliable low latency communications (URLLC). By incorporating strong security, communication reliability, and latency, a multi-objective optimization problem is investigated in the finite blocklength (FBL) regime. The derived optimization problem aims to maximize the secrecy rate by designing a secure precoder, while simultaneously minimizing both the maximum error probability and the rate of information leakage. The proposed FBL-based optimization algorithm provides the significantly improved tradeoff among the security, the error probability, and information leakage rate. Therefore, the proposed algorithms can offer significantly improved security for future wireless communication systems.clos