Generalized detector as a spectrum sensor in cognitive radio networks

The implementation of the generalized detector (GD) in cognitive radio (CR) systems allows us to improve the spectrum sensing performance in comparison with employment of the conventional detectors. We analyze the spectrum sensing performance for the uncorrelated and spatially correlated receive antenna array elements. Addi¬tionally, we consider a practical case when the noise power at the output of GD linear systems (the preliminary and additional filters) is differed by value. The choice of the optimal GD threshold based on the minimum total error rate criterion is also discussed. Simulation results demonstrate superiority of GD implementation in CR sys¬tem as spectrum sensor in comparison with the energy detector (ED), weighted ED (WED), maximum-minimum eigenvalue (MME) detector, and generalized likelihood ratio test (GLRT) detecto

Nonlinear Channel Equalization Approach for Microwave Communication Systems

The theoretical principles of intersymbol interference (ISI) and channel equalization in wireless communication systems are addressed. Several conventional and well-known equalization techniques are discussed and compared such as zero forcing (ZF) and maximum likelihood (ML). The main section in this chapter is devoted to an abstract concept of equalization approach, namely, dual channel equalization (DCE). The proposed approach is flexible and can be employed and integrated with other linear and nonlinear equalization approaches. Closed expressions for the achieved signal-to-noise ratio (SNR) and bit error rate (BER) in the case of ZF-DCE and ML-DCE are derived. According to the obtained outcomes, the DCE demonstrates promising improvements in the equalization performance (BER reduction) in comparison with the conventional techniques

Analyzing Chaos Systems and Fine Spectrum Sensing Using Detrended Fluctuation Analysis Algorithm

A numerical study that uses detrended fluctuation analysis (DFA) algorithm of time series obtained from linear and nonlinear dynamical systems is presented. The DFA algorithm behavior toward periodic and chaotic signals is investigated and the effect of the time scale under analysis is discussed. The displayed results prove that the DFA algorithm response is invariant (stable performance) to initial condition and chaotic system parameters. An initial idea of DFA algorithm implementation for fine spectrum sensing (SS) is proposed under two-stage spectrum sensor approach with test statistics based on the scaling exponent value. The outcomes demonstrate a promising new SS technique that can alleviate several imperfections such as noise power uncertainty and spatial correlation between the adjacent antenna array elements

Health Status of neolithic and eneolithic populations based on study of the skeletal material from Bohemia

There were used human skeletal remains from eight Older and Late Eneolithic burial sites from Bohemia to set their health status. I used remains of 307 individuals. Paleodemography analysis of cemeteries and cultures was made. There were shown possible modifications of life table values based on experiment with modern population values. During paleoepidemiological analysis I described the most important categories of pathological findings. The results of analysis were used to make comparisons between themselves and with individuals from the Moravian cemetery of Bell Beaker Culture from Hoštice I za Hanou. An unexpected result was the statistically significant difference in the height of Bohemian and Moravian population of Bell Beaker Culture. Male individuals of Funnel Beaker Culture had the lowest height of all. There were found only two congenital anomalies, plagiocephalia and Klippel-Feil syndrome (fused cervical vertebrae). X-ray images were made of the most important findings for better diagnosis. Except the classic categories of pathologies I detected two cases of hyperostosis frontalis interna, both females from a burial site of Corded Ware Culture in Vikletice. In five cases were found osteoplastic growth on the visceral surface of the ribs of individuals of Bell Beaker Culture from..

Antenna Arrays and Beam-formation

Spatial processing and smart antenna beam formation are considered as completely essential approaches to be employed for forthcoming progress in the standards and implementation of the wireless communication systems. The book aims, besides introducing up-to-date contributions that are not readily available in the related literature, to present and demonstrate the recent research ideas in the field of antenna array design and beam-forming algorithms in a synthetic, coherent, and unified manner for the interested researchers. The presented topics range from relatively straightforward mathematical analysis and derivations to simulation and empirical results. The book is designed to serve as an informative reference for the researcher involved in the analysis of the spatial signal processing techniques for smart antenna systems. The book will help the readers, in particular wireless communication researchers, to have wider futuristic and innovative visions for the advances in the field

Immune modulation in cardiovascular disease

The importance of the adaptive immune response in cardiovascular disease has been increasingly appreciated. However, limited information is available on immune modulation in the context of hypertension and atherosclerosis. In order to fill this knowledge gap, the amount of T regulatory (Treg) cells was determined by flow cytometry on cells from the spleen and the aorta in two murine models, namely angiotensin (Ang) II-induced hypertension (HT) and endothelin-1 (ET-1)-exacerbated high fat diet (HFD)-induced atherosclerosis in apolipoprotein E knockout (apoE-/-). Two groups of mice were studied. In the first study, 12-week old male C57BL/6 mice were infused with Ang II (1 µg/kg/min, s.c.) for 14 days via an osmotic pump or implanted with a dummy pump. In the second study, 8-week old C57BL/6 male transgenic mice with endothelium-restricted preproendothelin-1 (eET-1) overexpression, apoE-/-, eET-1/apoE-/- crosses, and wild type (WT) mice were fed a HFD or a normal diet (ND) for 8 weeks. A trend towards an increase in several T lymphocyte subpopulations including natural (CD4+CD25+Foxp3+) Tregs was observed in the spleen of mice infused with Ang II whereas in aorta natural Tregs tended to decrease. In atherosclerosis, an increase in classical (CD4+CD25+) Tregs was observed in the spleen of eET-1. HFD reduced the Treg content in the spleen of both WT and eET-1. In addition, HFD tended to increase natural Tregs in eET-1/apoE-/- crosses. In aorta, HFD increased classical Tregs and tended to increase natural Tregs in eET-1 whereas it tended to decrease natural Tregs in eET-1/apoE-/- crosses. The lack of significant change in the above studies limits drawing conclusions. However, the results suggest that ET-1 and HFD have an impact on Treg populations in the spleen and aorta. Additional animals and/or refinement in the techniques could lead to more definitive conclusions.Le rôle de la réponse immunitaire adaptative dans l'hypertension et l'athérosclérose commence à être apprécié. Cependant, il n'est pas clair que les lymphocytes T régulateurs (Tregs) jouent un rôle dans ces deux pathologies. Dans le but d'éclaircir le rôle de ces lymphocytes, le contenu en Tregs a été déterminé à l'aide de cytométrie de flux dans la rate et l'aorte de deux modèles murins, l'hypertension induite par l'angiotensine (Ang) II et l'athérosclérose induite par une diète riche en gras (DRG) dans des souris knockout pour l'apolipoprotéine E (apoE-/-) exagérée par la surexpression de l'endothéline (ET)-1. Deux groupes de souris ont été étudiés. Dans le premier groupe, des souris mâles C57BL/6 de 12 semaines ont été infusées ou pas avec de l'Ang II (1 µg/kg/min, s.c.) pendant 2 semaines. Dans le second groupe, des souris mâles C57BL/6 de 8 semaines transgéniques surexprimant l'ET-1 dans les cellules endothéliales (eET-1), apoE-/-, eET-1/apoE-/- et sauvages (WT) ont été nourries avec une DRG ou une diète normale (DN) pendant 8 semaines. Les souris infusées avec l'Ang II présentaient une tendance à l'augmentation de plusieurs sous-populations de lymphocytes T incluant les Tregs naturels (CD4+CD25+Foxp3+) dans la rate. Par contre, au niveau de l'aorte les Tregs naturels tendaient à diminuer. Dans l'étude de l'athérosclérose, une augmentation des Tregs (CD4+CD25+) a été observée dans la rate des souris eET-1. La DRG a réduit le contenu de Tregs dans la rate des souris WT et eET-1 et tendait à accroître les Tregs naturels dans la rate des eET-1/apoE-/-. Au niveau de l'aorte, la DRG a augmenté les Tregs et tendait à accroître les Tregs naturels dans les eET-1 et tendait à diminuer ces lymphocytes dans les eET-1/apoE-/-. Le manque de changements significatifs limite la possibilité de tirer des conclusions. Cependant, les résultats suggèrent que l'ET-1 et la DRG ont un impact sur la population de Tregs dans la rate et l'aorte. Des animaux additionnels et/ou un raffinement des techniques pourraient donner des résultats plus définitifs

Spectrum Sensing under Correlated Antenna Array Using Generalized Detector in Cognitive Radio Systems

We derive the probability of false alarm and detection threshold under employment of the generalized detector (GD) in cognitive radio (CR) systems for two scenarios: firstly, the independent antenna array elements; the secondly, the correlated antenna array elements. The energy detector (ED) and GD spectrum sensing performances are compared under the same initial conditions. The simulation results show that implementation of the GD improves the spectrum sensing performance in CR systems both for independent and correlated antenna array elements

SNR Wall Effect Alleviation by Generalized Detector Employed in Cognitive Radio Networks

The most commonly used spectrum sensing techniques in cognitive radio (CR) networks, such as the energy detector (ED), matched filter (MF), and others, suffer from the noise uncertainty and signal-to-noise ratio (SNR) wall phenomenon. These detectors cannot achieve the required signal detection performance regardless of the sensing time. In this paper, we explore a signal processing scheme, namely, the generalized detector (GD) constructed based on the generalized approach to signal processing (GASP) in noise, in spectrum sensing of CR network based on antenna array with the purpose to alleviate the SNR wall problem and improve the signal detection robustness under the low SNR. The simulation results confirm our theoretical issues and effectiveness of GD implementation in CR networks based on antenna array