Other affiliations: Ethiraj College for Women
Bio: K.V.N. Kavitha is an academic researcher from VIT University. The author has contributed to research in topics: Wireless & Wireless network. The author has an hindex of 6, co-authored 22 publications receiving 105 citations. Previous affiliations of K.V.N. Kavitha include Ethiraj College for Women.
TL;DR: A detailed survey of MIMO channel models in wireless communication systems is presented in this article, where the authors identify the three major models for the general multiple input multiple output (MIMO) channel models, viz., the physical, analytical, and standardized models.
Abstract: The field of wireless communication networks has witnessed a dramatic change over the last decade due to sophisticated technologies deployed to satisfy various demands peculiar to different data-intensive wireless applications. Consequently, this has led to the aggressive use of the available propagation channels to fulfill the minimum quality of service (QoS) requirement. A major barometer used to gauge the performance of a wireless communication system is the spectral efficiency (SE) of its communication channels. A key technology used to improve SE substantially is the multiple input multiple output (MIMO) technique. This article presents a detailed survey of MIMO channel models in wireless communication systems. First, we present the general MIMO channel model and identified three major MIMO channel models, viz., the physical, analytical, and standardized models. The physical models describe the MIMO channel using physical parameters. The analytical models show the statistical features of the MIMO channel with respect to the measured data. The standardized models provide a unified framework for modern radio propagation architecture, advanced signal processing, and cutting-edge multiple access techniques. Additionally, we examined the strengths and limitations of the existing channel models and discussed model design, development, parameterization, implementation, and validation. Finally, we present the recent 3GPP-based 3D channel model, the transitioning from 2D to 3D channel modeling, discuss open issues, and highlight vital lessons learned for future research exploration in MIMO communication systems.
••01 Feb 2014
TL;DR: The main aim of this paper is to contribute knowledge and services to the people of blind and disable society by providing more convenient means of life to the blind person.
Abstract: Independence is the building methodology in achieving dreams, goals and objectives in life. Visually impaired persons find themselves challenging to go out independently. There are millions of visually impaired or blind people in this world who are always in need of helping hands. For many years the white cane became a well-known attribute to blind person's navigation and later efforts have been made to improve the cane by adding remote sensor. Blind people have big problem when they walk on the street or stairs using white cane, but they have sharp haptic sensitivity. The electronic walking stick will help the blind person by providing more convenient means of life. The main aim of this paper is to contribute our knowledge and services to the people of blind and disable society.
TL;DR: In this paper, the authors present key areas of applications of cell-free massive MIMO in the ubiquitous 5G and the envisioned 6G wireless networks. And they highlight the research directions, open issues, and lessons learned to stimulate cutting-edge research in this emerging domain of wireless communications.
Abstract: In recent times, the rapid growth in mobile subscriptions and the associated demand for high data rates fuels the need for a robust wireless network design to meet the required capacity and coverage. Deploying massive numbers of cellular base stations (BSs) over a geographic area to fulfill high-capacity demands and broad network coverage is quite challenging due to inter-cell interference and significant rate variations. Cell-free massive MIMO (CF-mMIMO), a key enabler for 5G and 6G wireless networks, has been identified as an innovative technology to address this problem. In CF-mMIMO, many irregularly scattered single access points (APs) are linked to a central processing unit (CPU) via a backhaul network that coherently serves a limited number of mobile stations (MSs) to achieve high energy efficiency (EE) and spectral gains. This paper presents key areas of applications of CF-mMIMO in the ubiquitous 5G, and the envisioned 6G wireless networks. First, a foundational background on massive MIMO solutions-cellular massive MIMO, network MIMO, and CF-mMIMO is presented, focusing on the application areas and associated challenges. Additionally, CF-mMIMO architectures, design considerations, and system modeling are discussed extensively. Furthermore, the key areas of application of CF-mMIMO such as simultaneous wireless information and power transfer (SWIPT), channel hardening, hardware efficiency, power control, non-orthogonal multiple access (NOMA), spectral efficiency (SE), and EE are discussed exhaustively. Finally, the research directions, open issues, and lessons learned to stimulate cutting-edge research in this emerging domain of wireless communications are highlighted.
27 Oct 2009
TL;DR: This V2V wireless communication protocol provides a realistic simulation in Ns-2 for various topologies and the performances were evaluated for different parameters such as EWM delay, delay due to overhead packets and probability of successful delivery of the emergency warning message (EWM).
Abstract: More than 23% of annual vehicle accidents are rear-end collisions, this gives an important test-case for enhanced collision avoidance approaches based on v2v wireless communications. V2V wireless network concern with the impact of a IEEE 802.11 based multi-hop MAC protocol that propagates an emergency warning message (EWM) down a platoon of cars on a highway. The design objective is to ensure reception of this message with stringent delay constraints so as to provide drivers with requisite available manoeuvre time (AMT) to avoid rear-end collision. This V2V wireless communication protocol provides a realistic simulation in Ns-2 for various topologies (lane-1& lane-3) and the performances were evaluated for different parameters such as EWM delay, delay due to overhead packets and probability of successful delivery of the emergency warning message (EWM).
01 Jan 2011
TL;DR: In this paper, the physicochemical compatibility of the drug and polymers was studied by infrared spectroscopy, and the results suggested no physicochemical incompatibility between the drugs and the polymers.
Abstract: The purpose of this research work was to develop and evaluate matrix-type transdermal therapeutic system containing Nicardipine hydrochloride with different ratios of hydrophilic and hydrophobic polymeric combinations by the solvent evaporation technique. The physicochemical compatibility of the drug and the polymers was studied by infrared spectroscopy. The results suggested no physicochemical incompatibility between the drug and the polymers. Three transdermal patch formulations (F1, F2, F3) consists of Hydroxypropyl methylcellulose E5 and Ethyl cellulose in the ratios of 2:0, 0:2, and 1:1, respectively were prepared. All formulations carried dimethyl sulfoxide as penetration enhancer and dibutyl phthalate as plasticizer in acetone and methanol (4:3) as solvent system. The prepared transdermal patches were evaluated for in vitro release, moisture absorption, moisture loss and mechanical properties. The diffusion studies were performed by using modified Franz diffusion cells. The formulation, F1 (Hydroxypropyl methylcellulose E5 alone) showed maximum release of 97.1887 ± 0.568 % in 7 hrs, where as F2 (Ethyl cellulose alone) showed maximum release of 66.9393 ± 1.8120 % in 24 hrs. The formulation, F2 with combination of polymers (1:1) showed maximum release of 91.2275 ± 0.175 % in 24 hrs, emerging to be ideal formulations for Nicardipine hydrochloride. The developed transdermal patches increase the efficacy of Nicardipine hydrochloride for the therapy of hypertension, chronic stable angina pectoris, and Prinzmetal's variant angina.
01 Sep 2010
TL;DR: The various categories of applications in VANETs are introduced, as well as some security requirements, threats and certain architectures are proposed to solve the security problem.
TL;DR: A comprehensive overview of various radio channel access protocols and resource management approaches are provided, and their suitability for infotainment and safety service support in VANETs is discussed.
TL;DR: PPE reuse is a potential short term solution during COVID-19 pandemic where there is increased evidence for effective deployment of reprocessing methods such as vaporized hydrogen peroxide used alone or combined with ozone, ultraviolet light at 254 nm and moist heat.
TL;DR: An approach to the avoidance of rear-end collisions in congested traffic situations is presented and two fuzzy controllers, a Collision Warning System (CWS) and aCollision Avoidance System (cAS), have been developed and tested with two mass-produced cars.
Abstract: Highlights? We have implemented a rear-end collision warning/avoidance system in a real car. ? The system decides how to perform the maneuver without leaving the road. ? A vehicle-to-infrastructure communication system is used to exchange data. ? Fuzzy logic is used both for the warning and for the avoidance systems. ? Experiments with real cars were conducted with propper results. To decrease traffic accidents is a declared target of Intelligent Transportation Systems (ITS). Among them, rear-end collisions are one of the most common and constitute one of the as yet unsolved topics in the automotive sector. This paper presents an approach to the avoidance of rear-end collisions in congested traffic situations. To this end, two fuzzy controllers, a Collision Warning System (CWS) and a Collision Avoidance System (CAS), have been developed. The former is in charge of alerting the driver in case of an impending rear-end collision to prevent or mitigate the crash. The latter is in charge of generating an output control signal for the steering wheel in order to avoid the collision. Both CWS and CAS have been tested with real cars using vehicle-to-infrastructure (V2I) communications to acquire data of vehicles. A system installed in the infrastructure capable of assessing road traffic conditions in real time is responsible for transmitting the data of the vehicles in the surrounding area. The systems have been tested at the Center for Automation and Robotics (CAR)'s facilities with two mass-produced cars.