On a Non-linear Electronic Circuit Filtering

The stochastic versions of non-linear dynamic circuits are formalized using non-linear stochastic differential equations. Stochastic differential equations (SDEs) are exploited to analyse dynamical systems in noisy environments. A potential application of the SDEs can be regarded as ‘stochastic processes in electronic circuits’. The noisy sampling mixer, a component of digital wireless communications, is an appealing and standard case from the dynamical systems’ viewpoint. It assumes the structure of a non-linear SDE, and its linearized version becomes time-varying bilinear SDE. This paper derives the filtering equations for the noisy non-linear sampling mixer circuit utilizing the filtering density evolution equation. The filtering model for the stochastic problem of concern here comprises the following: (1) a non-linear SDE describing the noisy sampling mixer and (2) a non-linear noisy observation equation. It is interesting to note that the filtered estimate accounts for observations. On the other hand, the predicted estimate does not account for the observation terms in evolution equations. As a result of this, the filtered estimate confirms the greater accuracy of estimated state trajectory in contrast to the predicted trajectory. The filtering equation of this paper can be further utilized for control of the noisy sampling mixer, where the observations are available.     

A Markov Decision Process based flow assignment framework for heterogeneous network access

We consider a scenario where devices with multiple networking capabilities access networks with heterogeneous characteristics. In such a setting, we address the problem of efficient utilization of multiple access networks by devices via optimal assignment of traffic flows with given utilities to different networks. We develop and analyze a device middleware functionality that monitors network characteristics and employs a Markov Decision Process (MDP) based control scheme that in conjunction with stochastic characterization of the available bit rate and delay of the networks generates an optimal policy for allocation of flows to different networks. The optimal policy maximizes, under available bit rate and delay constraints on the access networks, a discounted reward which is a function of the flow utilities. The flow assignment policy is periodically updated and is consulted by the flows to dynamically perform network selection during their lifetimes. We perform measurement tests to collect traces of available bit rate and delay characteristics on Ethernet and WLAN networks on a work day in a corporate work environment. We implement our flow assignment framework in ns-2 and simulate the system performance for a set of elastic video-like flows using the collected traces. We demonstrate that the MDP based flow assignment policy leads to significant enhancement in the QoS provisioning (higher rate allocation, lower packet delays and packet loss rates) for the flows and better access network utilization, as compared to policies that allocate flows to different networks using greedy approaches or heuristics like average available bit rate on the networks.     

Multichannel ECG data compression based on multiscale principal component analysis

In this paper, multiscale principal component analysis (MSPCA) is proposed for multichannel electrocardiogram (MECG) data compression. In wavelet domain, principal components analysis (PCA) of multiscale multivariate matrices of multichannel signals helps reduce dimension and remove redundant information present in signals. The selection of principal components (PCs) is based on average fractional energy contribution of eigenvalue in a data matrix. Multichannel compression is implemented using uniform quantizer and entropy coding of PCA coefficients. The compressed signal quality is evaluated quantitatively using percentage root mean square difference (PRD), and wavelet energy-based diagnostic distortion (WEDD) measures. Using dataset from CSE multilead measurement library, multichannel compression ratio of 5.98:1 is found with PRD value 2.09% and the lowest WEDD value of 4.19%. Based on, gold standard subjective quality measure, the lowest mean opinion score error value of 5.56% is found.     

Self‐Assembled Room Temperature Multiferroic BiFeO3‐LiFe5O8 Nanocomposites

Multiferroic materials have driven significant research interest due to their promising technological potential. Developing new room‐temperature multiferroics and understanding their fundamental properties are important to reveal unanticipated physical phenomena and potential applications. Here, a new room temperature multiferroic nanocomposite comprised of an ordered ferrimagnetic spinel α‐LiFe₅O₈ (LFO) and a ferroelectric perovskite BiFeO₃ (BFO) is presented. It is observed that lithium (Li)‐doping in BFO favors the formation of LFO spinel as a secondary phase during the synthesis of Li_xBi_1?xFeO₃ ceramics. Multimodal functional and chemical imaging methods are used to map the relationship between doping‐induced phase separation and local ferroic properties in both the BFO‐LFO composite ceramics and self‐assembled nanocomposite thin films. The energetics of phase separation in Li doped BFO and the formation of BFO‐LFO composites are supported by first principles calculations. These findings shed light on Li's role in the formation of a functionally important room temperature multiferroic and open a new approach in the synthesis of light element doped nanocomposites for future energy, sensing, and memory applications.     

Encrypted Network Traffic Classification and Resource Allocation with Deep Learning in Software Defined Network

Wireless Personal Communications - The climate has changed absolutely in every area in just a few years as digitized, making high-speed internet service a significant need in the future. Future...     

The Ga−Sb (Gallium-Antimony) system

R. C. Sharma was Visiting Assistant Professor (1984–1986)     

Design and Analysis of MIMO Antenna with High Isolation and Dual Notched Band Characteristics for Wireless Applications

A very compact Superwideband multiple-input–multiple-output antenna with dual notched band characteristics is presented. Superwideband characteristics is obtained by means of radiating patch and high isolation between two input ports are obtained by using T-shaped stub in ground plane. Two rejection bands (wireless interoperability for microwave access (WiMAX)/C-band and wireless local area network) are obtained by etching two elliptical slots on radiating patch. Antenna offers large measured useable bandwidth of 2.60–20.04 GHz. Diversity performance is studied in terms of envelope correlation coefficient, diversity gain and total active reflection coefficient. Antenna also offers desirable radiation pattern, gain and radiation efficiency which makes proposed antenna quite suitable for different wireless applications.

     

G-FANET: an ambient network formation between ground and flying ad hoc networks

In wireless communications, both control information and payload (user-data) are concurrently transmitted and required to be successfully recovered. This paper focuses on block-level detection, which is applicable for detecting transmitted control information, particularly when this information is selected or chosen from a finite set of information that are known at both transmitting and receiving devices. Using an orthogonal frequency division multiplexing architecture, this paper investigates and evaluates the performance of a time-domain decision criterion in comparison with a form of Maximum Likelihood (ML) estimation method. Unlike the ML method, the proposed time-domain detection technique requires no channel estimation as it uses the correlation (in the time-domain) that exists between the received and the transmitted selective information as a means of detection. In comparison with the ML method, results show that the proposed method offers improved detection performance, particularly when the control information consists of at least 16. However, the implementation of the proposed method requires a slightly increased number of mathematical computations.     

Structural and Electrical Properties of Ag/<Emphasis Type="Italic">n</Emphasis>-TiO<Subscript>2</Subscript>/<Emphasis Type="Italic">p</Emphasis>-Si/Al Heterostructure Fabricated by Pulsed Laser Deposition Technique

We have investigated the structural and electrical characteristics of the Ag/n-TiO₂/p-Si/Al heterostructure. Thin films of pure TiO₂ were deposited on p-type silicon (100) by optimized pulsed laser ablation with a KrF-excimer laser in an oxygen-controlled environment. X-ray diffraction analysis showed the formation of crystalline TiO₂ film having a tetragonal texture with a strong (210) plane as the preferred direction. High purity aluminium and silver metals were deposited to obtain ohmic contacts on p-Si and n-TiO₂, respectively. The current–voltage (I–V) characteristics of the fabricated heterostructure were studied by using thermionic emission diffusion mechanism over the temperature range of 80–300 K. Parameters such as barrier height and ideality factor were derived from the measured I–V data of the heterostructure. The detailed analysis of I–V measurements revealed good rectifying behavior in the inhomogeneous Ag/n-TiO₂/p-Si(100)/Al heterostructure. The variations of barrier height and ideality factor with temperature and the non-linearity of the activation energy plot confirmed that barrier heights at the interface follow Gaussian distributions. The value of Richardson’s constant was found to be 6.73 × 10⁵ Am^?2 K^?2, which is of the order of the theoretical value 3.2 × 10⁵ Am^?2 K^?2. The capacitance–voltage (C–V) measurements of the heterostructure were investigated as a function of temperature. The frequency dependence (Mott–Schottky plot) of the C–V characteristics was also studied. These measurements indicate the occurrence of a built-in barrier and impurity concentration in TiO₂ film. The optical studies were also performed using a UV–Vis spectrophotometer. The optical band gap energy of TiO₂ films was found to be 3.60 eV.