Providing secure communications over the physical layer with objective of achieving secrecy without requiring a secret key has been receiving growing attention within past decade. The vast majority existing studies in area security focus exclusively on scenarios where channel inputs are Gaussian distributed. However, practice, signals employed for transmission drawn from discrete signal constellations such as phase shift keying and quadrature amplitude modulation. Hence, understanding impact...

We consider precoder and artificial noise (AN) design for multi-antenna wiretap channels under the finite-alphabet input assumption. assume that transmitter has access to channel coefficients of legitimate receiver knows statistics eavesdropper's channel. Accordingly, we propose a secrecy rate maximization algorithm using gradient descent-based optimization matrix an exhaustive search over power levels allocated AN. also algorithms reduce complexities direct ergodic by: 1) maximizing cut-off...

We investigate the effect of transmitter side channel state information on achievable secrecy rates space shift keying. Through derivation gradient rate, we formulate an iterative algorithm to maximize rates. also introduce two lower complexity signal design algorithms for different scenarios based number antennas at eavesdropper. Our results illustrate effectiveness proposed precoding techniques in attaining positive over a wide range noise ratios.

Surface defect detection plays a significant role in quality enhancement steel manufacturing. Support Vector Machines and neural networks are the most popular classifiers this application. Decision trees also known as other for yielding fast but moderate performance. In paper, we introduce more accurate classification method by using decision applying Principal Component Analysis (PCA) Bootstrap Aggregating (Bagging) on features being extracted local binary pattern based operator. This...

In this work, we propose an iterative scheme for computing a linear precoder that takes into account the impact of hardware impairments in multiuser multiple-input singleoutput downlink. We particularly focus on case when transmitter is equipped with nonlinear power amplifiers. Using Bussgang's theorem, formulate lower bound achievable sum rate presence impairments, and maximize it using projected gradient ascent. provide numerical examples demonstrate efficacy proposed distortion-aware...

Spatial modulation (SM) and space shift keying (SSK) represent transmission methods for low-complexity implementation of multiple-input multiple-output (MIMO) wireless systems in which antenna indices are employed data transmission. In this paper, we focus our attention on the secrecy behavior SSK SM. Using an information-theoretic framework, derive expressions mutual information consequently compute achievable rates SM via numerical evaluations. We also characterize by showing effects...

In this paper, we present a novel and effective linearization technique for nonlinear phased array antennas. For large arrays, of the using single digital predistortion (DPD) is inevitable since one path upconverted feeds several RF transmission paths, each which connected to power amplifier (PA) an antenna element. However, critical issue that PA characteristics can vary considerably within array. Thus, linearizing individual PAs with DPD rather challenging. We formulate solve optimization...

We introduce a framework for linear precoder design over massive multiple-input multiple-output downlink system in the presence of nonlinear power amplifiers (PAs). By studying spatial characteristics distortion, we demonstrate that conventional precoding techniques steer distortions towards users. show that, by taking into account PA nonlinearity, one can precoders reduce, and single-user scenarios, even completely remove distortion transmitted direction This, however, is achieved at price...

A hybrid optimization algorithm, including mutual coupling (MC), is proposed to synthesize an irregular sparse array (ISA) for average capacity maximization in a multiuser multiple-input–multiple-output (MU-MIMO) system. The approach composed of two phases suboptimally determine the location fixed number omnidirectional thin dipole antennas arbitrary aperture via diagonal antenna selection matrix. In Phase I, problem relaxed convex by ignoring MC and weakening constraints. output I accounted...

Location information is expected to be the key meeting needs of communication and context-aware services in 6G systems. User localization achieved based on delay and/or angle estimation using uplink or downlink pilot signals. However, hardware impairments (HWIs) distort signals at both transmitter receiver sides thus affect performance. While this impact can ignored lower frequencies where HWIs are less severe, modeling analysis efforts needed for evaluate degradation due HWIs. In work, we...

Practical codes for the Gaussian wiretap channel are designed aiming at satisfying information-theoretic metrics to ensure security against a passive eavesdropper (Eve). Specifically, design criterion is introduced coset coding scheme in order satisfy strong secrecy condition described with mutual information between secret message and Eve's observation. In addition, neural estimation (MINE) powered from deep learning tools applied directly compute constraint, verify proposed solutions. It...

We propose a low complexity transmit signal design scheme for achieving information-theoretic secrecy over MIMO wiretap channel driven by finite-alphabet inputs. assume that the transmitter has perfect state information (CSI) of main and also knows statistics eavesdropper's channel. The proposed transmission relies on jointly optimizing precoder matrix artificial noise so as to maximize achievable rates. In order lower computational associated with design, we employ metric using cut-off rate...

This letter presents a design of an electronically reconfigurable unit cell (UC), that can be used in the construction intelligent reflecting and refracting surfaces (IR <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> Ss) for future 6G communication. It independently perform beam forming or steering both reflection refraction modes. The IR S UC responds separately to TE TM incidences. utilizes PIN diodes obtain two phase states, 0° 180°...

Localization is envisioned as a key enabler to satisfy the requirements of communications and context-aware services in fifth/sixth generation (5G/6G) communication systems. User localization can be achieved based on delay angle estimation using uplink/downlink pilot signals. However, hardware impairments (HWIs) (such phase noise mutual coupling) distort signals at both transmitter receiver sides thus affect performance. While this impact ignored lower frequencies with less severe HWIs,...

We consider the uplink of a single-cell multi-user multiple-input multiple-output (MU-MIMO) system in presence nonlinear distortion at users and base station. Assuming orthogonal frequency-division multiplexing (OFDM) transmission, we leverage Bussgang's theorem to derive an equivalent linear model formulate distortion-aware minimum mean squared error (LMMSE)-based receiver. The accuracy proposed is verified via numerical experiments. Furthermore, our results reveal that LMMSE receiver can...

We present a framework for joint estimation and compensation of three major oscillator impairments, namely sampling time error (STE), carrier frequency offset (CFO) phase noise (PN). In particular, we model these impairments as Wiener processes introduce pilot-aided approach which facilitates their estimation. The proposed solution is carried out in two steps: first, an initial the transmitted symbols acquired by applying extended Kalman filter (EKF) on pilot then, second EKF applied...

We propose a secure transmission scheme based on space shift keying (SSK) in which the indices associated with transmit antennas are assigned dynamically according to channel towards legitimate receiver. first derive an asymptotic secrecy rate under perfect reciprocity assumption. Then, we study impacts of imperfect and presence nearby eavesdropper reliability eavesdropping resilience proposed scheme. Finally, introduce enhanced antenna index assignment algorithm is more robust reciprocity,...

Hardware impairments in general and amplifier nonlinearity particular severely limit the performance of communication links. This paper analytically provides statistical results on how a nonlinear affects quality signals systems. In particular, we propose model that describes distortion as function input signal's average instantaneous power captures pulse-shaping matched filters' effects. We show through simulations complementary measurements proposed can provide an authentic connection...

In this paper, we analyze the effects of hardware impairments on 77GHz FMCW automotive radar performance. Joint in-phase/quadrature imbalance (IQI) and phase noise frequency-modulated continuous-wave (FMCW) transceiver front-end are modeled through statistical analysis distortion noise. We derive signal to plus ratio, constant false alarm rate, range-Doppler sensitivity for both joint individual validate formulations with simulations. The represented modeling can be used in millimetre wave...

We propose transmit optimization techniques for multi-input multi-output (MIMO) wiretap channels with statistical channel state information (CSI) at the transmitter. consider doubly correlated towards legitimate receiver and eavesdropper. The aim is to maximize secrecy rates using knowledge of correlation matrices. develop gradient-descent based algorithms obtaining optimal signals both Gaussian finite-alphabet inputs. Furthermore, we introduce a joint precoder artificial noise (AN) design...

We provide a rigorous framework for characterizing and numerically evaluating the error probability achievable in uplink downlink of fully digital quantized multiuser multiple-input multiple-output (MIMO) system. assume that system operates over quasi-static channel does not change across finite-length transmitted codewords, only imperfect state information (CSI) is available at base station (BS) user equipments. The need novel developed this paper stems from fact that, scenario, commonly...

A new technique for the estimation of coupling between array elements in MIMO transceivers is presented. The method founded on subsequent transmission and over-the-air (OTA) reception elements, when transmitter's characteristics are unknown. enables accurate on-line characterization behavior terms a complete system with PAs antennas connected. validated via OTA measurements four-element transmitter configuration. results demonstrate that estimated couplings proposed similar to ones obtained...

In this paper, we statistically analyze the effect of hardware impairments on power pattern antenna array systems. We consider a linear and formulate stochastic beam as function variations in phase, gain element positions. By deriving closed-form expression for variance pattern, express how performance can be degraded each angle, allowing investigation role parameter final variations. The proposed serves tractable tool analyzing perturbations different settings.

Hardware impairments are the inevitable limiting factors in radio frequency communication systems, and particular mm-wave, can severely affect system performance. In this paper, we propose an additive noise modeling technique for analyzing residual hardware impairments, more accurately than previously done literature. We analyze effects of joint phase IQI both transmitter receiver by using as a representation method indicate how other be described same framework. derive signal to distortion...