Spectrum sensing is a key component of the cognitive radio paradigm. Primary signals are typically detected with uncalibrated receivers at signal-to-noise ratios (SNRs) well below decodability levels. Multiantenna detectors exploit spatial independence receiver thermal noise to boost detection performance and robustness. We study problem detecting Gaussian signal rank- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</i> unknown covariance matrix...

In this paper, the second-order circularity of quaternion random vectors is analyzed. Unlike case complex vectors, there exist three different kinds properness, which are based on vanishing complementary covariance matrices. The properness have direct implications Cayley-Dickson representation vector, and also several well-known multivariate statistical analysis methods. particular, extensions partial least squares (PLS), multiple linear regression (MLR) canonical correlation (CCA)...

Due to the heavy reliance of millimeter-wave (mmWave) wireless systems on directional links, beamforming (BF) with high-dimensional arrays is essential for cellular in these frequencies. Thus, performing array processing a power-efficient manner fundamental challenge. Analog and hybrid BF require few analog-to-digital digital-to-analog converters (ADCs DACs), but can only communicate small number directions at time, limiting search, spatial multiplexing, control signaling. Digital enables...

This work addresses the problem of deciding whether a set realizations vector-valued time series with unknown temporal correlation are spatially correlated or not. For wide sense stationary (WSS) Gaussian processes, this is between two different power spectral density matrices, one them diagonal. Specifically, we show that for arbitrary processes (not necessarily WSS) generalized likelihood ratio test (GLRT) given by quotient determinant sample space-time covariance matrix and its...

Spectrum sensing for cognitive radio requires effective monitoring of wide bandwidths, which translates into high-rate sampling. Traditional spectrum methods employing high-precision analog-to-digital converters (ADCs) result in increased power consumption and expensive hardware costs. In this paper, we explore blind utilizing one-bit ADCs. We derive a closed-form detector based on Rao's test demonstrate its equivalence with the second-order eigenvalue-moment-ratio test. Furthermore,...

Background: The emergence of smartphones, wearable sensor technologies, and smart homes allows the nonintrusive collection activity data. Thus, health-related events, such as activities daily living (ADLs; eg, mobility patterns, feeding, sleeping, ...) can be captured without patients' active participation. We designed a system to detect changes in patterns based on smartphone's native sensors advanced machine learning signal processing techniques. Objective: principal objective this work is...

Target detection is an important problem in multiple-input multiple-output (MIMO) radar. Many existing target algorithms were proposed without taking into consideration the quantization error caused by analog-to-digital converters (ADCs). This paper addresses of for MIMO radar with one-bit ADCs and derives a Rao's test-based detector. The method has several appealing features: 1) it closed-form detector; 2) allows us to handle sign measurements straightforwardly; 3) there are approximations...

Background Monitoring the emotional states of patients with psychiatric problems has always been challenging due to noncontinuous nature clinical assessments, effect health care environment, and inherent subjectivity evaluation instruments. However, mental in disorders exhibit substantial variability over time, making real-time monitoring crucial for preventing risky situations ensuring appropriate treatment. Objective This study aimed leverage new technologies deep learning techniques...

ABSTRACT Deadwood moisture affects multiple functions of downed logs in forest ecosystems. They include provision habitats for xylobionts, additional water stores and organic carbon stocks. In contrast to Northern American forests, little is known about variability important tree species within the Temperate Zone Europe. Therefore, our study aimed at elucidating this according species, site decay class (DC). Measurements were taken by TDR during two vegetation periods eight Carpathian...

In this paper, we study the existence of locally most powerful invariant tests (LMPIT) for problem testing covariance structure a set Gaussian random vectors. The LMPIT is optimal test case close hypotheses, among those satisfying invariances problem, and in practical scenarios can provide better performance than typically used generalized likelihood ratio (GLRT). derivation usually requires one to find maximal statistic detection then derive its distribution under both which general rather...

Hardware platforms and testbeds are an essential tool to evaluate, in realistic scenarios, the performance of wireless communications systems. In this work we present a multiuser Multiple-Input Multiple-Output (MIMO) testbed made up 6 nodes, each one with 4 antennas, which allows us evaluate Interference Alignment (IA) techniques indoor scenarios. We specifically study IA for 3-user interference channel 5GHz band. Our analysis identifies main practical issues that potentially degrade such as...

We report the design, fabrication, and test of an InGaAs avalanche photodiode (APD) for 950–1650 nm wavelength sensing applications. The APD is grown by molecular beam epitaxy on InP substrates from lattice-matched InAlAs alloys. Avalanche multiplication inside occurs in a series asymmetric gain stages whose layer ordering acts to enhance rate electron-initiated impact ionization suppress hole-initiated when operated at low gain. are cascaded series, interposed with carrier relaxation layers...

We demonstrate a nanopillar (NP) device structure for implementing plasmonically enhanced avalanche photodetector arrays with thin volumes (∼ 310 nm × 150 nm). A localized 3D electric field due to core–shell PN junction in NP acts as multiplication region, while efficient light absorption takes place via surface plasmon polariton Bloch wave (SPP-BW) modes self-aligned metal nanohole lattice. Avalanche gains of ∼216 at 730 −12 V are obtained. show through capacitance–voltage characterization,...

This paper derives an asymptotic generalized likelihood ratio test (GLRT) and locally most powerful invariant (LMPIT) for two hypothesis testing problems: 1) Is a vector-valued random process cyclostationary (CS) or is it wide-sense stationary (WSS)? 2) CS nonstationary? Our approach uses the relationship between scalar-valued time series WSS which knowledge of cycle period required. allows us to formulate problem as covariance structure observations. The matrix observations has...

The authors report a two-color, colocated quantum dot based imaging system used to take multicolor images using single focal plane array (FPA). dots-in-a-well (DWELL) detectors consist of an active region composed InAs dots embedded in In.15Ga.85As wells. DWELL samples were grown molecular beam epitaxy and fabricated into 320×256 arrays with indium bumps. FPA was then hybridized Indigo ISC9705 readout circuit tested. Calibrated blackbody measurements at device temperature 77K yield midwave...

The variability of suicidal thoughts and other clinical factors during follow-up has emerged as a promising phenotype to identify vulnerable patients through Ecological Momentary Assessment (EMA). In this study, we aimed (1) clusters variability, (2) examine the features associated with high variability. We studied set 275 adult treated for crisis in outpatient emergency psychiatric departments five centers across Spain France. Data included total 48,489 answers 32 EMA questions, well...

The coherence spectrum is a well-known measure of the linear statistical relationship between two time series. In this paper, we extend concept to several processes and define generalized magnitude squared (GMSC) as function largest eigenvalue matrix containing all pairwise complex spectra. GMSC bounded zero one, attains its maximum when are perfectly correlated at given frequency. Furthermore, three different estimators, extending those previously proposed for MSC processes, presented....

A resource-constrained system monitors a source of information by requesting finite number updates subject to random transmission delays. An priori fixed update request policy is shown minimize polynomial penalty function the age over arbitrary time horizons. Partial updates, compressed with reduced and content, in presented model are incur an independent compression. Finite horizons have better performance terms second order statistic relative infinite

In this paper, the basics and some of recent developments in quantum dots-in-a-well (DWELL) focal plane arrays (FPAs) are reviewed. Fundamentally, these detectors represent a hybrid between conventional well infrared photodetector (QWIP) dot (QDIP), which active region consists dots (QDs) embedded (QW). This hybridization grants DWELLs many advantages its components. These include normally incident photon sensitivity without gratings or optocoupers, like QDIPs, reproducible control over...

A multiple-input multiple-output (MIMO) frequency-domain channel measurement methodology is presented. This can be implemented in any transmit/receive hardware consisting of radio frequency modules and baseband digital processing units. It involves the transmission reception phase-optimized complex exponentials through antenna arrays, followed by an offline estimation, which makes additional synchronization circuitry unnecesary. To test feasibility this method, a series measurements...