A Cognitive Way to Access the Frequency Spectrum

Cognitive radio (CR) is an emergent technology in wireless communication. It aims at improve considerably spectrum use by allowing dynamic spectrum access (DSA). The DSA can be performed in different ways, e.g. interweave and underlay approach. In the interweave approach the CR systems can access frequency bands that are not occupied. In the underlay approach, CR systems can transmit over busy bands with a low power spectrum density. In this paper, a new architecture for CR system implementation with a hybrid DSA is proposed. To maintain stability and improve the spectrum efficiency, a system combining interweave and underlay approach is proposed. Using spectrum sensing the CR system determines the free and busy bands. Then, the system performs a classification method to obtain the modulation over the busy bands. Knowing the modulation, the system determines the maximum power to transmit. Over the free bands, the system use interweave approach meanwhile, an underlay approach is use to access the busy bands. When considering an OFDM CR system that cohabits with another OFDM system, simulation results show the performance of the proposed system.Cognitive radio (CR) is an emergent technology in wireless communication. It aims at improve considerably spectrum use by allowing dynamic spectrum access (DSA). The DSA can be performed in different ways, e.g. interweave and underlay approach. In the interweave approach the CR systems can access frequency bands that are not occupied. In the underlay approach, CR systems can transmit over busy bands with a low power spectrum density. In this paper, a new architecture for CR system implementation with a hybrid DSA is proposed. To maintain stability and improve the spectrum efficiency, a system combining interweave and underlay approach is proposed. Using spectrum sensing the CR system determines the free and busy bands. Then, the system performs a classification method to obtain the modulation over the busy bands. Knowing the modulation, the system determines the maximum power to transmit. Over the free bands, the system use interweave approach meanwhile, an underlay approach is use to access the busy bands. When considering an OFDM CR system that cohabits with another OFDM system, simulation results show the performance of the proposed system

A Context-Responsive LSTM based IoT Enabled E- Healthcare Monitoring System for Arrhythmia Detection

Detecting Arrhythmia, a life-threatening cardiac condition, in real-time is crucial for timely intervention and improved healthcare outcomes. Traditional manual methods for Arrhythmia detection using Electrocardiogram (ECG) signals are error-prone and resource-intensive. To address these limitations, this paper presents an automated system based on the Context Responsive Long Short-Term Memory (CR-LSTM) model for real-time Arrhythmia classification. The system leverages IoT technology to continuously monitor vital signs and effectively combines contextual information with temporal sensor data to accurately discern different types of Arrhythmias. The CR-LSTM model achieves an impressive accuracy of 99.72% in multiclass classification of Arrhythmias, making it a promising solution for dynamic healthcare settings and proactive personalized care

Defining equations of 77-dimensional model CR hypersurfaces and models in CN\mathbb{C}^{N}

We investigate a class of CR invariants of uniformly $2$-nondegenerate CR hypersurfaces, termed modified symbols, and develop methods for deriving defining equations of CR hypersurfaces realizing different values of these invariants. For hypersurfaces in $\mathbb{C}^4$, we obtain the full classification of modified symbols realizable by weighted homogeneous (with respect to a natural weighting system) rigid CR hypersurfaces, and obtain defining equations for the recently classified $7$-dimensional homogeneous modified symbol models. Moreover, we characterize, up to CR equivalence, all weighted homogeneous rigid uniformly $2$-nondegenerate CR hypersurfaces in $\mathbb{C}^{N}$ whose holomorphic infinitesimal symmetries generate a transitive action on their Levi leaf spaces.Comment: 37 pages, comments welcomed, auxiliary Maple files include

Evaluation of the Acute Oral Toxicity Class of Trinuclear Chromium(III) Glycinate Complex in Rat

Chromium(III) is considered as an essential element playing a role in carbohydrate and lipid metabolism, and various chemical forms of this element are widely used in dietary supplements. A new trinuclear chromium(III) glycinate complex [Cr3O(NH2CH2CO2)6(H2O)3]+NO3− (CrGly), an analogue of Cr3 (trinuclear Cr(III) propionate complex) has been synthesized as a potential source of supplementary Cr. In this study, we evaluated the acute toxicity class of CrGly in Wistar rats applying the OECD 423 procedure. Male and female Wistar rats (n = 12, 6 ♀ and 6 ♂) were given by gavage either a single dose of CrGly 2,000 mg/kg body mass (equals to 300 mg Cr(III)/kg body mass; in aqueous solution) or equivalent volumes of distilled water and fed ad libitum commercial Labofeed B diet, and observed carefully for 14 days, then sacrificed to collect blood and internal organs for biochemical and histologic examination. No death cases were detected. No abnormalities in animal behavior, body mass gains, gross organ histology, or blood morphology and biochemistry were observed. The results demonstrate that LD50 of CrGly is greater than 2,000 mg/kg when administrated orally to rat; thus, this compound appears to belong to the fifth category in the GHS system or the fourth class (“unclassified”) in the EU classification system

Pseudohermitian invariants and classification of CR mappings in generalized ellipsoids

We discuss the problem of classifying all local CR diffeomorphisms of a strictly pseudoconvex surface. Our method exploits the Tanaka--Webster pseudohermitian invariants, their transformation formulae, and the Chern--Moser invariants. Our main application concerns a class of generalized ellipsoids where we classify all local CR mappings.Comment: Accepted version, to appear on J. Math. Soc. Japa