Navegando por Assunto "Redes ad hoc (redes de computadores)"

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Acesso aberto (Open Access)
Análise do impacto do algoritmo de escalonamento de recursos no desempenho de redes veiculares utilizando o LTE como tecnologia de acesso
(Universidade Federal do Pará, 2016-08-11) CARDOSO, Evelin Helena Silva; FRANCÊS, Carlos Renato Lisboa; http://lattes.cnpq.br/7458287841862567
Intelligent Transport Systems are several information and communication technologies applied to vehicular transportation. It is called intelligent due to its memory capacity, sensing, communication, information processing and adaptive behavior. Within this universe, the Vehicular Ad-hoc Networks (VANET) provide communication between vehicles, as well as the telecommunications infrastructure over the roads. In order to achieve connectivity continues with high data rate and low latency, the integration of vehicular networks with LTE system is pointed as a potential access technology solution. There are many challenges found to reach the QoS requirements characteristic of entertainment applications, road safety and traffic efficiency. Therefore, this dissertation proposes a methodology for the study of the impact of radio resource scheduling algorithms for vehicular networks using LTE as the access technology. This study uses a discrete simulation approach, carried out with NS-3 and SUMO tools, to evaluate five scheduling algorithms: RR, PF, TTA, CQA and PSS. The criteria used in the analysis are throughput, delay, packet loss, spectral efficiency, fairness and qualitative analysis of computational complexity. The results indicate for vehicular networks is more appropriate to apply strategies that guarantee high level of fairness between connected vehicles. The evaluation also confirm the need to use algorithms more specific, taking into account the data generation pattern of these kind of application, with the aim to ensure the best performance for the network.
Acesso aberto (Open Access)
Controle de qualidade de experiência para disseminação de vídeos em tempo real sobre redes ad hoc veiculares
(Universidade Federal do Pará, 2017-03-24) QUADROS, Carlos Jean Ferreira de; SANTOS, Aldri Luis dos; CERQUEIRA, Eduardo Coelho; http://lattes.cnpq.br/1028151705135221
Live video dissemination over Vehicular Ad hoc Networks (VANETs) is fundamental for several services, e.g., roadside video emergency, advertisement's broadcast, and smart video surveillance. All these applications face many challenges due to stringent video quality level requirements, dynamic topologies, and broadcast environments. To deal with these challenges, as well as reduce network routing overhead, geographic Statistical Routing Protocols (SRPs) have been proposed as a suitable solution for the distribution of video flows in VANETs, usually by using positioning and Quality of Service (QoS) parameters. However, rather than only these parameters, a satisfactory video dissemination from the user's perspective also requires video and human-awareness issues. In real situations, due to different requirements and hierarchical structures of multimedia applications, network level and position parameters alone are not enough to select the best relay nodes and build up reliable routes to multi-hop video dissemination with satisfactory reachability and Quality of Experience (QoE) levels. This thesis focuses on improving the disseminated quality of on-road live videos in VANETs. Thus, we propose the cross-layer Broadcast Receiver-based and QoE-driven (BRQ) mechanism, which is modularly coupled to SRPs to offer QoE-aware and video-related parameters for the relay node selection and route maintenance. Thus, nodes decide for themselves to retransmit further the video sequences, enhancing the capacity of the system in delivering videos with better QoE assurance. On top of this, an application-level Error-Control (EC) scheme, namely Interleaving, allows mitigating the effects of frame loss. BRQ was added to a straightforward SRP built using the Distance method, named DBRQ protocol. Results show the gains of DBRQ compared to current SRPs, achieving video dissemination with QoE support, less routing overhead, and satisfactory reachability.
Acesso aberto (Open Access)
Mecanismo de roteamento cross-layer em redes móveis Ad Hoc sem fio: um modelo de inteligência computacional com eficiência energética e suporte a mobilidade e QoE
(Universidade Federal do Pará, 2016-03-18) CARVALHO, Tássio Costa de; FRANCÊS, Carlos Renato Lisboa; http://lattes.cnpq.br/7458287841862567
The evolution of wireless communications technologies has led to the need to provide network support for data and video applications and thus promote the development of new types of network configurations adapted to these new requirements. MANET is an important type of operation networks that employs mechanisms that can enable dynamic autoconfiguration, which requires a higher efficiency of its routing protocols. These protocols can also be challenged due to energy failures that are becoming increasingly severe in relation to the common networks failure; furthermore, the quality of the multimedia stream corresponds to a fundamental premise to the next generation wireless networks and the future Internet. This thesis proposes a new routing mechanism based on cross-layer paradigm to enhance the main routing protocols, by inserting new metrics in a computational intelligence decision making based on fuzzy systems, providing energy efficiency, support to manage mobility and quality experience to the devices, choosing the best route for the flow of computer networks. The proposal is evaluated in network simulator, demonstrating its efficiency through network results, quality of experience metrics and maximizing the communication’s lifetime.