841 research outputs found

    Network emulation focusing on QoS-Oriented satellite communication

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    This chapter proposes network emulation basics and a complete case study of QoS-oriented Satellite Communication

    W-NINE: a two-stage emulation platform for mobile and wireless systems

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    More and more applications and protocols are now running on wireless networks. Testing the implementation of such applications and protocols is a real challenge as the position of the mobile terminals and environmental effects strongly affect the overall performance. Network emulation is often perceived as a good trade-off between experiments on operational wireless networks and discrete-event simulations on Opnet or ns-2. However, ensuring repeatability and realism in network emulation while taking into account mobility in a wireless environment is very difficult. This paper proposes a network emulation platform, called W-NINE, based on off-line computations preceding online pattern-based traffic shaping. The underlying concepts of repeatability, dynamicity, accuracy and realism are defined in the emulation context. Two different simple case studies illustrate the validity of our approach with respect to these concepts

    Two-stage wireless network emulation

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    Testing and deploying mobile wireless networks and applications are very challenging tasks, due to the network size and administration as well as node mobility management. Well known simulation tools provide a more flexible environment but they do not run in real time and they rely on models of the developed system rather than on the system itself. Emulation is a hybrid approach allowing real application and traffic to be run over a simulated network, at the expense of accuracy when the number of nodes is too important. In this paper, emulation is split in two stages : first, the simulation of network conditions is precomputed so that it does not undergo real-time constraints that decrease its accuracy ; second, real applications and traffic are run on an emulation platform where the precomputed events are scheduled in soft real-time. This allows the use of accurate models for node mobility, radio signal propagation and communication stacks. An example shows that a simple situation can be simply tested with real applications and traffic while relying on accurate models. The consistency between the simulation results and the emulated conditions is also illustrated

    WIRELESS NETWORK STUDY AND ANALYSIS USING NS2 SIMULATOR

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    NS2 (Network Simulation version 2) is a well-known generic network simulator. Unlike other expensive simulation software, it is free and based on open source. It is widely used to simulate and emulate communication networks. Furthermore, it has a rich library of network and protocol objects, which almost involve most of the aspects of network technology. This makes NS2 the most favorable simulation software which is widely used in academic research. On the other hand, the results of the simulation are validated by many research centers. For this reason many published articles about network technology show their results by using NS2 simulation. Additionally, act an excellent instruction tool NS2 is widely utilized in education. Nowadays, NS2 becomes more and more popular in scientific research and education. Nevertheless, NS2 is quite difficult to handle for a beginner. Some reasons are: the content of NS2 is very huge; the official NS manual is not updated regularly and a lot of relative knowledge and tools are involved to operate NS2 efficiently. NS2 will be one of the main tools in the research activities of the Telecommunication Engineering Group (TEG). Hence, the main target of this thesis is to study NS2 deeply and to show how to construct an emulation environment by using NS2 and MATLAB. Different simulators are given to demonstrate how to proceed with NS2. This thesis will be one reference for TEG researches for the applications of NS2.fi=OpinnÀytetyö kokotekstinÀ PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=LÀrdomsprov tillgÀngligt som fulltext i PDF-format

    IREEL: remote experimentation with real protocols and applications over emulated network

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    This paper presents a novel e-learning platform called IREEL. IREEL is a virtual laboratory allowing students to drive experiments with real Internet applications and end-to-end protocols in the context of networking courses. This platform consists in a remote network emulator offering a set of predefined applications and protocol mechanisms. Experimenters configure and control the emulation and the end-systems behavior in order to perform tests, measurements and observations on protocols or applications operating under controlled specific networking conditions. A set of end-to-end mechanisms, mainly focusing on transport and application level protocols, are currently available. IREEL is scalable and easy to use thanks to an ergonomic web interface

    An autonomic delivery framework for HTTP adaptive streaming in multicast-enabled multimedia access networks

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    The consumption of multimedia services over HTTP-based delivery mechanisms has recently gained popularity due to their increased flexibility and reliability. Traditional broadcast TV channels are now offered over the Internet, in order to support Live TV for a broad range of consumer devices. Moreover, service providers can greatly benefit from offering external live content (e. g., YouTube, Hulu) in a managed way. Recently, HTTP Adaptive Streaming (HAS) techniques have been proposed in which video clients dynamically adapt their requested video quality level based on the current network and device state. Unlike linear TV, traditional HTTP- and HAS-based video streaming services depend on unicast sessions, leading to a network traffic load proportional to the number of multimedia consumers. In this paper we propose a novel HAS-based video delivery architecture, which features intelligent multicasting and caching in order to decrease the required bandwidth considerably in a Live TV scenario. Furthermore we discuss the autonomic selection of multicasted content to support Video on Demand (VoD) sessions. Experiments were conducted on a large scale and realistic emulation environment and compared with a traditional HAS-based media delivery setup using only unicast connections
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