scholarly journals Robust Security Beamforming for SWIPT-Assisted Relay System with Channel Uncertainty

Sensors ◽  
2022 ◽  
Vol 22 (1) ◽  
pp. 370
Author(s):  
Ruijie Guo ◽  
Chunling Fu ◽  
Yong Jin ◽  
Zhentao Hu ◽  
Lin Zhou
Keyword(s):  
Physical Layer Security ◽  
Original Problem ◽  
Superior Performance ◽  
Direct Link ◽  
Worst Case ◽  
Convex Optimization Problem ◽  
Maximum Security ◽  
Slack Variable ◽  
Status Information ◽  
Robust Beamformer

This paper considers the physical layer security (PLS) of a simultaneous wireless information and power transfer (SWIPT) relay communication system composed of a legitimate source–destination pair and some eavesdroppers. Supposing a disturbance of channel status information (CSI) between relay and eavesdroppers in a bounded ellipse, we intend to design a robust beamformer to maximum security rate in the worst case on the constraints of relay energy consumption. To handle this non-convex optimization problem, we introduce a slack variable to transform the original problem into two sub-problems firstly, then an algorithm employing a semidefinite relaxation (SDR) technique and S-procedure is proposed to tackle above two sub-problems. Although our study was conducted in the scene of a direct link among source, destination, and eavesdroppers that is non-existing, we demonstrate that our conclusions can be easily extended to the scene for which a direct link among source, destination and eavesdroppers exist. Numerical simulation results compared with the benchmark scheme are provided to prove the effectiveness and superior performance of our algorithm.

scholarly journals A RECONSIDERATION OF THE DOCTRINAL FOUNDATIONS OF MONETARY POLICY RULES: FISHER VERSUS CHICAGO

2021 ◽  
Vol 43 (1) ◽  
pp. 55-82
Author(s):  
George S. Tavlas
Keyword(s):  
Monetary Policy ◽  
Price Level ◽  
Policy Instruments ◽  
Policy Instrument ◽  
Superior Performance ◽  
Policy Uncertainty ◽  
Direct Link ◽  
Policy Rule ◽  
Policy Rules ◽  
Monetary Policy Rules

There has long been a presumption that the price-level stabilization frameworks of Irving Fisher and Chicagoans Henry Simons and Lloyd Mints were essentially equivalent. I show that there were subtle, but important, differences in the rationales underlying the policies of Fisher and the Chicagoans. Fisher’s framework involved substantial discretion in the setting of the policy instruments; for the Chicagoans the objective of a policy rule was to tie the hands of the authorities in order to reduce discretion and, thus, monetary policy uncertainty. In contrast to Fisher, the Chicagoans provided assessments of the workings of alternative rules, assessed various criteria—including simplicity and reduction of political pressures—in the specification of rules, and concluded that rules would provide superior performance compared with discretion. Each of these characteristics provided a direct link to the rules-based framework of Milton Friedman. Like Friedman’s framework, Simons’s preferred rule targeted a policy instrument.

scholarly journals Robust Synthesis Algorithm for Directional Modulation Signal with Array Manifold Vectors Uncertainty

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Tao Hong
Keyword(s):  
Physical Layer Security ◽  
Euclidean Distance ◽  
Inequality Constraint ◽  
Sidelobe Level ◽  
Worst Case ◽  
Synthesis Algorithm ◽  
Modulation Signal ◽  
New Research ◽  
Directional Modulation ◽  
Robust Synthesis

Directional modulation (DM) has become a new research hotspot of physical layer security (PLS) communication at the transmitter side. In this paper, we propose a robust synthesis algorithm for DM signal under the condition of the array manifold vectors perturbation. This algorithm optimizes the constraints of sidelobe level and Euclidean distance of constellation points by considering the worst case performance of array manifold vectors. Furthermore, we also design an active constellation extension (ACE) method to relax the equality constraint of desired modulation symbols into a robust inequality constraint at the desired direction. These constraints can be reformulated in a convex form with l2 and l∞ regularization, which are computationally tractable. Simulation results show better performance of the proposed robust algorithm compared with the benchmark synthesis algorithms in the presence of array manifold vectors uncertainty.

scholarly journals A Reconsideration of the Doctrinal Foundations of Monetary-Policy Rules: Fisher versus Chicago

2021 ◽  
Author(s):  
George S. Tavlas
Keyword(s):  
Monetary Policy ◽  
Price Level ◽  
Policy Instruments ◽  
Policy Instrument ◽  
Superior Performance ◽  
Policy Uncertainty ◽  
Direct Link ◽  
Policy Rule ◽  
Policy Rules ◽  
Monetary Policy Rules

There has long been a presumption that the price-level-stabilization frameworks of Irving Fisher and Chicagoans Henry Simons and Lloyd Mints were essentially equivalent. I show that there were subtle, but important, differences in the rationales underlying the policies of Fisher and the Chicagoans. Fisher’s framework involved substantial discretion in the setting of the policy instruments; for the Chicagoans the objective of a policy rule was to tie the hands of the authorities in order to reduce discretion and, thus, monetary-policy uncertainty. In contrast to Fisher, the Chicagoans provided assessments of the workings of alternative rules, assessed various criteria -- including simplicity and reduction of political pressures -- in the specification of rules, and concluded that rules would provide superior performance compared with discretion. Each of these characteristics provided a direct link to the rules-based framework of Milton Friedman. Like Friedman’s framework, Simons’s preferred rule targeted a policy instrument.

A Multi-Stage Optimization Approach for Energy Supply Systems With Discrete Design Decisions

2019 ◽  
Author(s):  
S. Bruche ◽  
G. Tsatsaronis
Keyword(s):  
Energy Supply ◽  
Original Problem ◽  
Superior Performance ◽  
Mixed Integer ◽  
Optimization Models ◽  
Optimization Approach ◽  
Energy Supply System ◽  
Multi Stage ◽  
Supply Systems ◽  
Energy Supply Systems

Abstract Mixed integer linear programming is frequently applied to identify promising design solutions of energy supply systems. However, application-relevant optimization models are often associated with complicating model features, e.g. numerous discrete design candidates or a large time horizon of the optimization. So, even state-of-the-art solvers may be confronted with major challenges to find satisfying solutions within reasonable time. In this paper a systematic multi-stage optimization approach is proposed that is intended to support the available algorithms in solving these complex problems. The basic idea of the approach is the distribution of the original problem into two major levels. On the first level, promising design candidates are generated using simplified optimization models. These simplifications are achieved through time series aggregation and the relaxation of operational binary variables. In the second stage, the objective values of the design candidates for the original problem are determined. The division of the problem into two stages leads to a significant reduction in required optimization time but simultaneously leads to an uncertainty regarding the quality of the found solution. Therefore, in a subsequent step, it is checked whether the objective value is within an acceptable distance from the theoretically best solution. If this is not the case, the first two steps are iteratively repeated. The proposed multi-stage approach is applied to the optimization of an energy supply system located in Germany. The results show a superior performance regarding required optimization time over conventional methods.

scholarly journals Data Rate Maximization in RIS-Assisted D2D Communication with Transceiver Hardware Impairments

Electronics ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 200
Author(s):  
Hongxia Zheng ◽  
Chiya Zhang ◽  
Yatao Yang ◽  
Xingquan Li ◽  
Chunlong He
Keyword(s):  
Optimization Problem ◽  
Original Problem ◽  
Optimal Solution ◽  
Base Station ◽  
D2d Communication ◽  
Convex Optimization Problem ◽  
Hardware Impairments ◽  
Convex Problems ◽  
Rate Maximization ◽  
Power Limit

We maximize the transmit rate of device-to-device (D2D) in a reconfigurable intelligent surface (RIS) assisted D2D communication system by satisfying the unit-modulus constraints of reflectin elements, the transmit power limit of base station (BS) and the transmitter in a D2D pair. Since it is a non-convex optimization problem, the block coordinate descent (BCD) technique is adopted to decouple this problem into three subproblems. Then, the non-convex subproblems are approximated into convex problems by using successive convex approximation (SCA) and penalty convex-concave procedure (CCP) techniques. Finally, the optimal solution of original problem is obtained by iteratively optimizing the subproblems. Simulation results reveal the validity of the algorithm that we proposed to solve the optimization problem and illustrate the effectiveness of RIS to improve the transmit rate of the D2D pair even with hardware impairments.

New algorithms for pattern matching with wildcards and length constraints

2015 ◽  
Vol 07 (03) ◽  
pp. 1550032 ◽  
Author(s):  
Abdullah N. Arslan ◽  
Betsy George ◽  
Kirsten Stor
Keyword(s):  
Pattern Matching ◽  
Polynomial Time ◽  
Original Problem ◽  
Heuristic Algorithms ◽  
Optimal Solution ◽  
Exact Algorithm ◽  
Exact Algorithms ◽  
Worst Case ◽  
Special Cases ◽  
New Algorithms

The pattern matching with wildcards and length constraints problem is an interesting problem in the literature whose computational complexity is still open. There are polynomial time exact algorithms for its special cases. There are heuristic algorithms, and online algorithms that do not guarantee an optimal solution to the original problem. We consider two special cases of the problem for which we develop offline solutions. We give an algorithm for one case with provably better worst case time complexity compared to existing algorithms. We present the first exact algorithm for the second case. This algorithm uses integer linear programming (ILP) and it takes polynomial time under certain conditions.

scholarly journals Split Antenna Array in Millimeter Wave for Secure Vehicular Communication

2018 ◽  
Vol 173 ◽  
pp. 02024
Author(s):  
Shah Marjan ◽  
Lin Bai ◽  
Chao Han
Keyword(s):  
Millimeter Wave ◽  
Antenna Arrays ◽  
Physical Layer Security ◽  
Communication Systems ◽  
Physical Layer ◽  
Directional Antennas ◽  
Phase Shifters ◽  
Superior Performance ◽  
Artificial Noise ◽  
Vehicular Communication

The small carrier wavelength at millimeter wave (mm-wave) frequencies features a large number of co-located antennas. Wireless networks with directional antennas using beamforming at mm-wave also have potential to provide an enhanced security in the vehicular communication system. Large bandwidth of mm-wave can provide auto drive and safety linked functionalities, However, safety and efficiency of the vehicular transportation system can be jeopardized by many kinds of attacks by eavesdroppers, physical layer security can work as an extra layer of security for wireless communication systems. To secure communication in-between Vehicles, an Analog precoding based physical Layer technique for mm-wave vehicular communication systems is presented in the paper. The proposed technique works by exploiting large Antenna arrays at millimeter waves and provide a secure directional transmission with low power consuming phase shifters and single Radio Frequency Chain. Larger antennas arrays are split into two subsets, one for transmission of data and another for generating noise. The proposed technique offers improved coherent transmission at the legitimate receiver and by introducing artificial noise to the eavesdroppers at random directions. This outcome in low SNR for the eavesdroppers, hence hacking information becomes extremely difficult. Numerical and Simulation results show the superior performance of the proposed technique compared to traditional physical layer security technique and conventional array technique.

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