1,287 research outputs found
IP-Level Satellite Link Emulation with KauNet
Distributed applications and transport protocols communicating over a satellite link may react very strongly to conditions specific to that kind of link. Providing a evaluation framework to allow tests of real implementations of such software in that context is quite a challenging task. In this paper we demonstrate how the use of the general-purpose KauNet IP-level emulator combined with satellite-specific packet loss patterns can help by reproducing losses and delays experienced on a satellite link with a simple Ethernet LAN setup. Such a platform is an essential tool for developers performing continuous testing as they provide new features for e.g. video codecs or transport-level software like DCCP and its congestion control components
The Dynamics of Vehicular Networks in Urban Environments
Vehicular Ad hoc NETworks (VANETs) have emerged as a platform to support
intelligent inter-vehicle communication and improve traffic safety and
performance. The road-constrained, high mobility of vehicles, their unbounded
power source, and the emergence of roadside wireless infrastructures make
VANETs a challenging research topic. A key to the development of protocols for
inter-vehicle communication and services lies in the knowledge of the
topological characteristics of the VANET communication graph. This paper
explores the dynamics of VANETs in urban environments and investigates the
impact of these findings in the design of VANET routing protocols. Using both
real and realistic mobility traces, we study the networking shape of VANETs
under different transmission and market penetration ranges. Given that a number
of RSUs have to be deployed for disseminating information to vehicles in an
urban area, we also study their impact on vehicular connectivity. Through
extensive simulations we investigate the performance of VANET routing protocols
by exploiting the knowledge of VANET graphs analysis.Comment: Revised our testbed with even more realistic mobility traces. Used
the location of real Wi-Fi hotspots to simulate RSUs in our study. Used a
larger, real mobility trace set, from taxis in Shanghai. Examine the
implications of our findings in the design of VANET routing protocols by
implementing in ns-3 two routing protocols (GPCR & VADD). Updated the
bibliography section with new research work
Reliable communication stack for flexible probe vehicle data collection in vehicular ad hoc networks
Towards a network management solution for vehicular delay-tolerant networks
Vehicular networks appeared as a new communication solution where vehicles act as a communication infrastructure, providing data communications through vehicle-to-vehicle (V2V) or vehicle-to-infrastructure (V2I) communications. Vehicular Delay-Tolerant Networks (VDTNs) are a new disruptive network architecture assuming delay tolerant networking paradigm where there are no end-to-end connectivity. In this case the incial node transmits the data to a closed node, the data will be carried by vehicles, hop to hop until the destination.
This dissertation focuses on a proposal of a network management solution, based standard protocol Simple Network Management Protocol (SNMP) to VDTN networks. The developed solution allows control a VDTN netowork through a Network Management System (NMS) with the objective to detect and, if it’s possible, anticipate, possible errors on network.
The research methodology used was the prototyping. So, it was built a network management module to the laboratorial prototype, called VDTN@Lab. The system built include a MIB (Management Information Base) placed in all vehicular network nodes. The solution was built, demonstrated, validated and evaluated their performance, being ready for use.As redes veiculares foram desenhadas para permitir que os veĂculos possam
transportar dados criando assim um novo tipo de redes, caracterizando-se por dois tipos de
comunicação: comunicações veĂculo-para-veĂculo (V2V) ou comunicações veĂculo-parainfra-estrutura (V2I). Redes veiculares intermitentes (do InglĂŞs Vehicular Delay-Tolerant
Networks - VDTNs) surgiram como uma nova arquitectura de rede de dados onde os
veĂculos sĂŁo utilizados como infra-estruturas de comunicação. As VDTNs caracterizam-se
por serem redes veiculares baseadas no paradigma de comunicações intermitentes. Nas
redes VDTN não existe uma ligação permanente extremo a extremo entre o emissor e o
receptor. Neste caso, o nĂł inicial transmite os dados para um nĂł que esteja junto dele e
assim sucessivamente, os dados vĂŁo sendo transportados pelos veĂculos, salto a salto atĂ©
ao destinatário final.
Esta dissertação centra-se na proposta de uma solução de gestão de rede, baseada
no protocolo estandardizado Simple Network Management Protocol (SNMP) para redes
VDTN. A solução construĂda permite controlar uma rede VDTN atravĂ©s de um sistema de
gestĂŁo de rede (do InglĂŞs Network Management System - NMS) com o objectivo de
detectar e, se possĂvel antecipar, possĂveis erros na rede.
A metodologia de investigação utilizada foi a prototipagem. Assim, foi construĂdo
um mĂłdulo de gestĂŁo de redes para o protĂłtipo laboratorial, chamado VDTN@Lab. O
sistema construĂdo inclui uma MIB (Management Information Base) que Ă© colocada em
todos os nĂłs de uma rede veicular, tanto fixos como mĂłveis. A solução foi construĂda,
demonstrada, validade e avaliado o seu desempenho, estando assim pronta para ser
utilizada
Opportunistic Networks: Present Scenario- A Mirror Review
Opportunistic Network is form of Delay Tolerant Network (DTN) and regarded as extension to Mobile Ad Hoc Network. OPPNETS are designed to operate especially in those environments which are surrounded by various issues like- High Error Rate, Intermittent Connectivity, High Delay and no defined route between source to destination node. OPPNETS works on the principle of “Store-and-Forward” mechanism as intermediate nodes perform the task of routing from node to node. The intermediate nodes store the messages in their memory until the suitable node is not located in communication range to transfer the message to the destination. OPPNETs suffer from various issues like High Delay, Energy Efficiency of Nodes, Security, High Error Rate and High Latency. The aim of this research paper is to overview various routing protocols available till date for OPPNETs and classify the protocols in terms of their performance. The paper also gives quick review of various Mobility Models and Simulation tools available for OPPNETs simulation
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