Search results for "communications"

Efficient distributed average consensus in wireless sensor networks

2020

International audience; Computing the distributed average consensus in Wireless Sensor Networks (WSNs) is investigated in this article. This problem, which is both natural and important, plays a significant role in various application fields such as mobile agents and fleet vehicle coordination, network synchronization, distributed voting and decision, load balancing of divisible loads in distributed computing network systems, and so on. By and large, the average consensus' objective is to have all nodes in the network converged to the average value of the initial nodes' measurements based only on local nodes' information states. In this paper, we introduce a fully distributed algorithm to a…

Robust H-Infinity Filter Design for Uncertain Linear Systems Over Network with Network-Induced Delays and Output Quantization

2009

This paper investigates a convex optimization approach to the problem of robust H-Infinity filtering for uncertain linear systems connected over a common digital communication network. We consider the case where quantizers are static and the parameter uncertainties are norm bounded. Firstly, we propose a new model to investigate the effect of both the output quantization levels and the network conditions. Secondly, by introducing a descriptor technique, using Lyapunov-Krasovskii functional and a suitable change of variables, new required sufficient conditions are established in terms of delay-dependent linear matrix inequalities (LMIs) for the existence of the desired network-based quantize…

2015

Visuo-auditory sensory substitution systems are augmented reality devices that translate a video stream into an audio stream in order to help the blind in daily tasks requiring visuo-spatial information. In this work, we present both a new mobile device and a transcoding method specifically designed to sonify moving objects. Frame differencing is used to extract spatial features from the video stream and two-dimensional spatial information is converted into audio cues using pitch, interaural time difference and interaural level difference. Using numerical methods, we attempt to reconstruct visuo-spatial information based on audio signals generated from various video stimuli. We show that de…

Steered Response Power Localization of Acoustic Passband Signals

2017

The vast majority of localization approaches using phase transform (PHAT) consider that the sources of interest are wideband low-pass sources. While this may be the usual case for common audio signals such as speech, PHAT methods are affected negatively by modulation artifacts when the sources to be localized are passband signals. In these cases, steered response power PHAT localization becomes less robust. This letter analyzes the form of generalized cross-correlation functions with PHAT when passband acoustic signals are considered, proposing approaches for increasing the localization performance through the mitigation of these negative effects.

On the Design of Probe Signals in Wireless Acoustic Sensor Networks Self-Positioning Algorithms

2018

A wireless acoustic sensor network comprises a distributed group of devices equipped with audio transducers. Typically, these devices can interoperate with each other using wireless links and perform collaborative audio signal processing. Ranging and self-positioning of the network nodes are examples of tasks that can be carried out collaboratively using acoustic signals. However, the environmental conditions can distort the emitted signals and complicate the ranging process. In this context, the selection of proper acoustic signals can facilitate the attainment of this goal and improve the localization accuracy. This letter deals with the design and evaluation of acoustic probe signals all…

Doppler Estimation and Correction for JANUS Underwater Communications

2020

In recent years, underwater communications have seen a growing interest pushed by marine research, oceanography, marine commercial operations, offshore oil industry and defense applications. Generally, underwater communications employ audio signals which can propagate relatively far but are also significantly affected by Doppler distortions. In fact, physical properties of the water and spatial changes due to tides, currents and waves can cause channel variations or unwanted movements of the transmitter or receiver. This study shows how to compensate for the Doppler effect in transmission employing the JANUS standard, a popular modulation scheme for underwater communication. Differently for…

On the feasibility of personal audio systems over a network of distributed loudspeakers

2018

Los sistemas de reproducción de audio personal se ocupan de la creación de zonas sonoras personales dentro de una habitación sin necesidad de utilizar auriculares. Estos sistemas utilizan un conjunto de altavoces y diseñan los filtros necesarios en cada altavoz con el fin de que la señal de audio deseada llegue a cada persona en la sala lo más libre de interferencias posible. Existen propuestas muy interesantes en la literatura que hacen uso de arrays circulares o lineales, pero en este trabajo estudiamos el problema considerando una red de altavoces distribuidos controlados por un conjunto de nodos acústicos, que pueden intercambiar información a través de una red. Enunciamos el modelo de …

Organizational information and communication technologies and their influence on communication visibility and perceived proximity

2021

This study investigates the relationships between the use of various organizational ICTs, communication visibility, and perceived proximity to distant colleagues. In addition, this study examines the interplay between visibility and proximity, to determine whether visibility improves proximity, or vice versa. These relationships are tested in a global company using two waves of panel survey data. ESM use increases communication visibility and perceived proximity, while controlling for prior levels of visibility, proximity, and the use of other organizational ICTs. The influence of ESM on network translucence and perceived proximity is generally stronger than the impact of other technologie…

Fingerprint Quality Evaluation in a Novel Embedded Authentication System for Mobile Users

2015

The way people access resources, data and services, is radically changing using modern mobile technologies. In this scenario, biometry is a good solution for security issues even if its performance is influenced by the acquired data quality. In this paper, a novel embedded automatic fingerprint authentication system (AFAS) for mobile users is described. The goal of the proposed system is to improve the performance of a standard embedded AFAS in order to enable its employment in mobile devices architectures. The system is focused on the quality evaluation of the raw acquired fingerprint, identifying areas of poor quality. Using this approach, no image enhancement process is needed after the …

A distributed detection and prevention scheme from malicious nodes in vehicular networks

2016

Summary Vehicular environments still remain vulnerable to various potential attacks because of continuous interactions and information exchange between vehicles despite the deployment of authentication techniques by communication standards. Therefore, an authenticated node with a certificate could initiate an attack while complying with implemented protocols. Some mechanisms were proposed to enhance communication technologies, but none of them was able to anticipate nodes' behavior. They also mismanage oscillating vehicles, because they evict them automatically after misbehaving. In this paper, we propose a preventive mechanism, namely, Intrusion Prevention and Detection System (IPDS), able…