The Rydberg atomic receiver (RARE) has garnered increasing attention in quantum communication due to its capability for high-precision signal sensing and detection. Recent advancements have led to the integration of RARE into multiple-input multiple-output (MIMO) systems. Signal detection in RARE MIMO systems presents a distinct biased phase retrieval (PR) challenge compared to conventional MIMO detection problems associated with radio frequency (RF) chains, rendering many traditional high-performance MIMO detectors inapplicable. This paper investigates the multiuser RARE MIMO problem under M -ary phase-shift keying (MPSK) modulations. The central challenge is to jointly address the biased PR formulation and the discrete MPSK constellation—an area not extensively explored in existing literature. We develop a custom approach that employs a smoothing technique to alleviate the nonsmoothness in the biased PR objective and a penalty transformation to tackle the discrete MPSK structure. The resulting algorithm combines a Majorization-Minimization (MM) framework with a modified Wirtinger flow (WF) method. Numerical simulations demonstrate that our proposed approach achieves superior detection accuracy compared to state-of-the-art detectors while maintaining lower computational complexity.

Massive multiple-input multiple-output (MIMO) technology has revolutionized wireless communication by significantly enhancing spectral efficiency, however its high energy consumption has become a key concern. There is increasing research interest in implementing massive MIMO systems using low-resolution digital-to-analog converters (DACs) to reduce the hardware cost and energy consumption. Meanwhile, the broadcast nature of wireless communications systems poses security risks, exposing user information to potential eavesdroppers (Eve), and this issue has been studied less in the context of low-resolution massive MIMO systems. This paper investigates the potential of low-resolution massive MIMO systems to enhance physical layer security (PLS) without relying on artificial noise (AN). We propose a novel spatial Sigma-Delta modulation technique that strategically leverages quantization noise to obscure confidential communications from Eve, even with limited channel state information. Our design shifts quantization noise away from legitimate users while maintaining its presence near Eve, thus improving PLS. We formulate the resulting non-convex, semi-infinite design problem and apply a proximal majorization-minimization (PMM) algorithm, ensuring convergence to a Karush–Kuhn–Tucker (KKT) point. To enhance computational efficiency, we introduce a proximal distance algorithm (PDA) that addresses the constraints independently, yielding closed-form solutions for projections and proximal operators. Extensive numerical experiments validate our approach, demonstrating effective noise shaping for both users and Eve. Our findings illustrate that quantization noise can be a valuable asset in securing communications in low-resolution massive MIMO systems.

In this paper, a novel synchronization learning scheme is proposed for secure communication, where the signal transmission architecture with a chaotic encryption process is considered. Firstly, to realize the information security in communication, the original signals are encrypted by fractional order dynamics from the sender, and decrypted by receiver to achieve synchronization. For the process, a hybrid order dynamic optimization is constructed, where the fractional order and the integer order systems are modeled as constraints. Secondly, a transformation formula is developed to convert these constraints into new integer order dynamics, and the equivalence between two dynamic optimizations is obtained. Thirdly, to obtain the synchronization solution, a new iterative learning algorithm is designed, and the adaptive dynamic programming is successfully embedded into the solving process. Finally, we apply the proposed synchronization scheme into the secure image transmission, and the simulation results demonstrate the effectiveness and practicality successfully.

The focus of this article is on the consensus problem of the multiagent system (MAS) with binary-valued quantized data under data tampering attacks. First, the properties of data tampering attacks are analyzed, and sufficient conditions are provided under which the attacks can effectively disrupt the consensus algorithm. Subsequently, inspired by the scheme of hierarchical estimation, a multitime scale consensus algorithm is proposed, enabling the MAS to achieve mean square consensus in the presence of tampering attacks. Next, the convergence speed of the consensus algorithm is analyzed, and it is demonstrated that the algorithm designed in this article retains the same upper bound for convergence speed under attacks as the two-time scale consensus algorithm without attacks. Finally, the effectiveness of the proposed method are validated through a signal frequency consensus experiment of the uncrewed aerial vehicles swarm system.

In this article, for the single-input–single-output (SISO) nonlinear strict-feedback system, optimized backstepping (OB) control combined with the dynamic surface (DS) technique is developed. OB is to make every subsystem control of backstepping as the optimized one so as to ensure the entire backstepping control being optimized. However, the original design of OB still needs to repeatedly calculate the derivative of virtual controls, as a result, it will inevitably cause the problem of “differential explosion.” In order to alleviate the phenomenon, the OB control is combined with the DS technique. Furthermore, OB control needs to conduct with reinforcement learning (RL) in every backstepping step, hence simplifying the algorithm of RL is very necessary and substantive for achieving the combination. In this work, because the optimized control derives both critic and actor training laws by utilizing a simple positive function instead of the square of approximation of Hamilton–Jacobi–Bellman (HJB) equation, it can obviously simplify the RL algorithm to compare with the traditional optimizing methods. Finally, the feasibility is illustrated via both theory and simulation.

This article addresses the security issue against data tampering attacks in the identification of finite impulse response (FIR) systems with binary-valued observations. First, the data tampering rate and estimation error caused by the network attack are derived. From the perspective of the attacker, it is investigated how to achieve the maximum attack effect with the minimum energy. Second, the compensation-type defense scheme is designed. Under this, the identification algorithm is constructed, and its strong convergence is proved. Taking the covariance matrix of the estimation error as the performance index, the optimal defense scheme is given. Finally, the results obtained are verified by simulation example.

In this article, adaptive tracking control of finite impulse response (FIR) systems is studied with binary-valued measurements. An adaptive control strategy is proposed based on an online identification algorithm. First, the designed control inputs are proved to be bounded and satisfy a persistent excitation (PE) condition under the assumption of periodic and PE target signals, which ensures the convergence of the identification algorithm. Second, the convergence rate of the identification algorithm is proved to be O(1/t) and it depends on the true parameter instead of a priori information of the parameter, which is more intuitive. Due to the convergence and the convergence rate of the identification algorithm, we finally prove that the adaptive tracking control is asymptotically optimal and the tracking speed is faster than the previous control algorithm. The simulations are given to validate the developed results in this article.

This paper considers the identification problem of finite impulse response (FIR) systems with binary-valued observations under the assumption of fixed threshold and bounded persistently excitations. A recursive projection algorithm is constructed to estimate the unknown parameter. For first-order FIR systems, the convergence properties of the algorithm are analyzed theoretically. With mild conditions on the weight coefficients in the parameter update, the algorithm is proved to be convergent in mean square and the convergence rate can be the reciprocal of the number of observations, which has the same order as the optimal estimation when the system output is exactly known. Furthermore, it is also shown that the Cramér-Rao (CR) lower bound is achieved asymptotically with proper weight coefficients, which indicates that the algorithm is optimal in the sense of asymptotic efficiency. Some numerical examples are simulated to demonstrate the effectiveness of the proposed algorithm in both first-order and high-order FIR systems.

This paper investigates the identification of the finite impulse response (FIR) systems with binary-valued observations. Combining with the stochastic gradient algorithm and statistical property of the system noise, a recursive projection algorithm is proposed to estimate the unknown parameters. Under some mild conditions on the a priori knowledge of the unknown parameters and inputs, the algorithm is proved to be convergent in the almost sure and mean square sense. Furthermore, the almost sure and mean square convergence rates of estimation errors are also obtained, and the schemes of selecting the quantization value are provided to ensure such rates. A numerical example is given to demonstrate the effectiveness of the algorithm and the main results obtained.