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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Performance analysis of transmission protocols for H.265 encoder

UMESH, AKELLA January 2015 (has links)
In recent years there has been a predominant increase in multimedia services such as live streaming, Video on Demand (VoD), video conferencing, videos for the learning. Streaming of high quality videos has become a challenge for service providers to enhance the user’s watching experience. The service providers cannot guarantee the perceived quality. In order to enhance the user’s expectations, it is also important to estimate the quality of video perceived by the user. There are different video streaming protocols that are used to stream from server to client. In this research, we aren’t focused on the user’s experience. We are mainly focused on the performance behavior of the protocols. In this study, we investigate the performance of the HTTP, RTSP and WebRTC protocols when streaming is carried out for H.265 encoder. The study addresses for the objective assessment of different protocols over VoD streaming at the network and application layers. Packet loss and delay variations are altered at the network layer using network emulator NetEm when streaming from server to client. The metrics at the network layer and application layer are collected and analyzed. The video is streamed from server to a client, the quality of the video is checked by some of the users. The research method has been carried out using an experimental testbed. The metrics such as packet counts at network layer and stream bitrate at application layer are collected for HTTP, RTSP and WebRTC protocols. Variable delays and packet losses are injected into the network to emulate real world. Based on the results obtained, it was found at the application layer that, out of the three protocols, HTTP, RTSP and WebRTC, the stream bitrate of the video transmitted using HTTP was less when compared to the other. Hence, HTTP performs better in the application layer. At the network layer, the packet counts of the video transmitted were collected using TCP port for HTTP and UDP port for RTSP and WebRTC protocols. The performance of HTTP was found to be stable in most of the scenarios. On comparing RTSP and WebRTC, the number of packet counts collected were more in number for RTSP when compared to WebRTC. This is because, the protocol and also the streamer are using more resources to transmit the video. Hence, both the protocols RTSP and WebRTC are performing better relatively.
2

Approaches and Techniques to Assess the Accuracy of Network Emulators / Tillvägagångssätt och tekniker för att bedöma hur exakta nätverksemulatorer är

Ekblad, Alice, Höglund, Anna January 2023 (has links)
As the mobile communication world expands in size and complexity, the need for testing the solutions in a controlled environment before deployment is as pronounced as ever. Simultaneously, new tools and products are developed to optimize the process and reduce costs. One tool that allows for testing the system under varying network conditions during development is a network emulator, which lies in between a classic network simulator and real-world network testing, providing high flexibility and repeatability in experiments and is expected to behave closer to a real-world network than a network simulator would. One established network emulator is the Itrinegy Network Emulator (INE). This paid product comes with a physical device and a software GUI and has been on the market for almost two decades. On the other end of the network emulation spectrum, the Znail Network Emulator is found: an open-source software-based network emulator designed to run on a single-board computer (e.g., a Raspberry Pi), which has been developed in the last five years in a nonenterprise-manner. In this thesis, these two network emulators are evaluated and compared against each other, aiming to investigate what functionality they offer and evaluate their emulation accuracy level. To do this, a testbed is set up to perform experiments by sending network traffic from a client to a server. The network emulator is placed between the hosts, acting as a bridge and applying different network conditions to the passing network traffic. The functionality comparison demonstrates that Znail offers minimal configuration options compared to the INE: only the most basic network conditions can be achieved with Znail. The results from the testbed experiments show that both emulators perform well when only one network parameter is applied at a time. However, when using more complex configurations with combinations of multiple network parameters, INE is overall superior in accuracy and stability, and Znail is deficient in several sectors. Although, the results also show that INE has some frailties in achieving correct emulation accuracy when combined with low bandwidth levels. Through the emulator functionality comparison and accuracy evaluation, this thesis argues that Znail can be a good choice of emulator in smaller establishments and for the at-home developer, while the INE is a better choice for larger organizations where stability and reliability are crucial.
3

Peripheral Nervous Network Simulator : A Computer Networks approach

Hmidi, Baha Eddine January 2022 (has links)
The peripheral nervous system can be seen as a huge network of neurons that prop-agates signals across the human body. In fact, as seen in [1] , "All the information streaming in the peripheral nervous system (PNS) is transmitted along axons byelectro-chemical signals called action potentials". The ordinary conduction of such nervous signals, or action potentials, can be prevented however due to nerve damage. In this context, the accurate passage of information to an intended destination or partwithin the organism is obstructed. Admittedly, it is understood that physiotherapy can be quite helpful in regaining correct functionality over a damaged part of the peripheral nervous system. Yet, it is still hard to visualize the nervous activity as it is achieved inside the human body. Simulating the nervous system would providea platform to visualize how the system works and how a damaged nerve can affect the PNS. Indeed, the purpose of this study is to simulate a virtual network that im-itates a general topology of the human peripheral nervous system e.g(simulate the nervous structure and behaviour of the human arm) that shows how the signals canbe routed to their correct destination and showcase how can the simulator created simulate biological nerve damage in its system.
4

The Impact of Waiting Time Distributions on QoE of Task-Based Web Browsing Sessions / Påverkan av väntetiden distributioner på QoE av Task-Based Web webbläsning

Islam, Nazrul, Elepe, Vijaya John David January 2014 (has links)
There has been an enormous growth in the Internet usage in recent years, fueled by the increasing number of multimedia applications and widespread availability of World Wide Web (WWW). The end-user generally accesses these applications through web browsing activities. These time-critical services often suffer from the delays ranging from small chunks to long peaks which can have severe implications on the Quality of Experience (QoE). Hence, it is worthwhile to identify the impact of different variations of delay on the end-user QoE. This research focused on the end-user QoE for three different distributions of delays occurring during an e-commerce shopping experiment. By keeping the overall waiting time of every sessions same, the study shows that the end-user QoE is different for different variety of delays. And the research also concludes that, the users prefer small frequently occurring delays as compared to the long rarely occurring delays within a task-driven web browsing session.

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