ISPCell: an interactive image-based streaming protocol for wireless cellular networks

Remote interaction with immersive 3D environments with acceptable level of quality of experience has become a challenging and interesting research topic. Due to the high data volume required to provide a rich experience to the user, robust and effcient wireless transport protocols have yet to be developed. On the other hand, cellular network technology has been widely deployed and is growing fast. The provision of remote interactive 3D environments over wireless cellular networks has several interesting applications, and it imposes some unsolved issues. Node mobility creates unstable bandwidth, which is a problem when providing smooth interaction to users. Although PDAs and cell phones are low resource devices, which makes it prohibitive to load and render entire virtual environments, they can still render images with relative ease. Based on this idea, this paper proposes a streaming system which relies on an image-based rendering approach, and is composed of several modules: a packetization scheme for images, an image-based rendering approach based on view morphing and its corresponding RTP payload format, and finally a bandwidth feedback mechanism and rate control. This paper illustrates some of the problems faced in this area, and provides a first step towards their solutions. We discuss our algorithms and present a set of simulation experiments to evaluate the performance of the proposed schemes.8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI

ISPCell: an interactive image-based streaming protocol for wireless cellular networks

Remote interaction with immersive 3D environments with acceptable level of quality of experience has become a challenging and interesting research topic. Due to the high data volume required to provide a rich experience to the user, robust and effcient wireless transport protocols have yet to be developed. On the other hand, cellular network technology has been widely deployed and is growing fast. The provision of remote interactive 3D environments over wireless cellular networks has several interesting applications, and it imposes some unsolved issues. Node mobility creates unstable bandwidth, which is a problem when providing smooth interaction to users. Although PDAs and cell phones are low resource devices, which makes it prohibitive to load and render entire virtual environments, they can still render images with relative ease. Based on this idea, this paper proposes a streaming system which relies on an image-based rendering approach, and is composed of several modules: a packetization scheme for images, an image-based rendering approach based on view morphing and its corresponding RTP payload format, and finally a bandwidth feedback mechanism and rate control. This paper illustrates some of the problems faced in this area, and provides a first step towards their solutions. We discuss our algorithms and present a set of simulation experiments to evaluate the performance of the proposed schemes.8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI

An energy efficient joint localization and synchronization solution for wireless sensor networks using unmanned aerial vehicle

Localization and synchronization are fundamental services for many applications in wireless sensor networks (WSNs), since it is often required to know the sensor nodes’ position and global time to relate a given event detection to a specific location and time. However, the localization and synchronization tasks are often performed after the sensor nodes’ deployment on the sensor field. Since manual configuration of sensor nodes is usually an impractical activity, it is necessary to rely on specific algorithms to solve both localization and clock synchronization problems of sensor nodes. With this in mind, in this work we propose a joint solution for the problem of 3D localization and time synchronization in WSNs using an unmanned aerial vehicle (UAV). A UAV equipped with GPS flies over the sensor field broadcasting its geographical position. Therefore, sensor nodes are able to estimate their geographical position and global time without the need of equipping them with a GPS device. Through simulation experiments, we show that our proposed joint solution reduces time synchronization and localization errors as well as energy consumption when compared to solutions found in the literature.FAPESP (processes 2012/22550-0 and 2013/05403-66)CNPq, CAPES, FAPEMIG (process APQ-01947-12)Natural Sciences and Engineering Research Council of Canada (NSERC

Especificação e implementação de um protocolo tolerante a falhas e de baixa latência para redes de sensores sem fio.

Wireless sensor networks are increasingly being deployed for fine-grain monitoring of physical environments subjected to critical conditions such as fire, leaking of toxic gases and explosions. A great challenge to these networks is to provide a fast, reliable and fault tolerant channel for event propagation. The protocol has to meet the requirements of querybased, event-driven and periodic sensor network application scenarios, even in the presence of emergency conditions that can lead to node failures and path disruption to the sink that receives those events. This paper presents a fault tolerant and low latency routing protocol that meets the sensor networks requirements for critical condition monitoring applications. The algorithm uses the publish/subscribe mechanism and the concept of event driven delivery, a technique that selects the shortest path for the notification of events, reducing latency. Fault tolerance is achieved through the triggering of a local path repair mechanism to find new paths with minimal number of transmissions. The protocol was implemented and simulated in the ns-2 network simulator and compared to the Directed Diffusion paradigm. Relevant metrics, such as end-to-end delay, energy dissipation, and delivery ratio, were evaluated showing that the proposed algorithm can be an adequate solution to meet the strict requirements of information propagation in real-time monitoring applications. An extension of the proposed protocol is also presented. This extension is in phase of implementation and simulation and it is expected to reduce data traffic and, consequently, reduce the energy dissipation. This new solution follows a hierarchical approach to propagate data through the network.As redes de sensores sem fio estão cada vez mais sendo aplicadas para o monitoramento preciso de ambientes físicos sujeitos a situações criticas como incêndios, vazamento de gases tóxicos e explosões. Um grande desafio para essas redes é oferecer um canal rápido, confiável e tolerante a falhas para a difusão dos dados coletados, que atenda aos requisitos dos diferentes tipos de monitoramento, como periódico, baseado em consultas e dirigido a eventos, mesmo na presença de condições de emergência que podem causar falhas nos nós sensores e interrupção de caminhos de entrega de dados. Este trabalho apresenta um protocolo de roteamento de baixa latência e tolerante a falhas que atende os requisitos das aplicações de redes de sensores, especialmente as aplicações de monitoramento de condições críticas. O algoritmo de roteamento utiliza o mecanismo publish/subscribe e o conceito de entrega dirigida a eventos, uma técnica que seleciona o caminho mais curto para a notificação de eventos, reduzindo a latência. A tolerância a falhas é acionada localmente por nós que detectam alguma falha em um nó vizinho. O protocolo foi implementado e simulado no simulador de redes ns-2 e comparado ao conhecido paradigma Directed Diffusion. Métricas importantes, como atraso fim-a-fim, consumo de energia e taxa de sucesso no recebimento de pacotes, foram avaliadas demonstrando que o protocolo proposto pode ser uma solução apropriada para atender aos rigorosos requisitos de propagação de informações em aplicações de monitoramento em tempo real. É apresentada também uma extensão do protocolo proposto. Essa extensão está em fase de implementação e simulação e espera-se que reduza o trafego de dados e, conseqüentemente, o consumo de energia. Essa nova solução segue uma abordagem hierárquica para a propagação de dados na rede

A Client-Server Approach to Enhance Interactive Virtual Environments on Mobile Devices over Wireless Ad Hoc Networks

Abstract. Interactive 3D environments have been studied for years and represent an important application area of computer graphics. However, high quality virtual environment interaction requires powerful computers equipped with expensive graphics accelerator cards. The high 3D data volume and the dynamic nature of bandwidth pose significant challenges when providing a smooth virtual navigation on thin mobile devices over wireless ad hoc networks. In this paper, we show that it is possible to provide a virtual environment walkthrough on mobile devices through a client-server approach. Although mobile devices have low processing power and memory, they can still render images with relative ease. Based on this fact, instead of using traditional geometry-rendering techniques and locally rendering complex scenes, we employ an image-based mechanism on the client that uses images, which are provided by a remote server through an interactive streaming transport protocol. In this paper, we propose a bandwidth feedback algorithm together with a rate control and virtual user path prediction to better adapt the system to the changing bandwidth. We also discuss our ideas and show an extensive set of simulations in order to evaluate the performance of our solutions