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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

QoE evaluation across a range of user age groups in video applications

Roshan, Mujtaba January 2018 (has links)
Quality of Service (QoS) measures are the network parameters; delay, jitter, and loss and they do not reflect the actual quality of the service received by the end user. To get an actual view of the performance from a user's perspective, the Quality of the Experience (QoE) measure is now used. Traditionally, QoS network measurements are carried on actual network components, such as the routers and switches since these are the key network components. In this thesis, however, the experimentation has been done on real video traffic. The experimental setup made use of a very popular network tool, Network Emulator (NetEm) created by the Linux Foundation. NetEm allows network emulation without using the actual network devices such as the routers and traffic generator. The common NetEm offered features are those that have been used by the researchers in the past. These have the same limitation as a traditional simulator, which is the inability of NetEm delay jitter model to represent realistic network traffic models, such to reflect the behaviour of real world networks. The NetEm default method of inputting delay and jitter adds or subtracts a fixed amount of delay on the outgoing traffic. NetEm also allows the user to add this variation in a correlated fashion. However, using this technique the outputted packet delays are generated in such a way as to be very limited and hence not much like real internet traffic which has a vast range of delays. The standard alternative that NetEm allows is generate the delays from either a Normal (Gaussian) or Pareto distribution. This research, however, has shown that using a Gaussian or Pareto distribution also has very severe limitations, and these are fully discussed and described in Chapter 5 on page 68 of this thesis. This research adopts another approach that is also allowed (with more difficulty) by NetEm: by measuring a very large number of packet delays generated from a double exponential distribution a packet delay profile is created that far better imitates the actual delays seen in Internet traffic. In this thesis a large set of statistical delay values were gathered and used to create delay distribution tables. Additionally, to overcome another default behaviour of NetEm of re-ordering packets once jitter is implemented, PFIFO queuing discipline has been deployed to retain the original packet order regardless of the highest levels of implemented jitter. Furthermore, this advancement in NetEm's functionality also incorporates the ability to combine delay, jitter, and loss, which is not allowed on NetEm by default. In the literature, no work has been found to have utilised NetEm previously with such an advancement. Focusing on Video On Demand (VOD) it was discovered that the reported QoE may differ widely for users of different age groups, and that the most demanding age group (the youngest) can require an order of magnitude lower PLP to achieve the same QoE than is required by the most widely studied age group of users. A bottleneck TCP model was then used to evaluate the capacity cost of achieving an order of magnitude decrease in PLP, and found it be (almost always) a 3-fold increase in link capacity that was required. The results are potentially very useful to service providers and network designers to be able to provide a satisfactory service to their customers, and in return, maintaining a prosperous business.
2

Efficient Resource Management for Video Applications in the Era of Internet-of-Things (IoT)

Perala, Sai Saketh Nandan 01 May 2018 (has links)
The Internet-of-Things (IoT) is a network of interconnected devices with sensing, monitoring and processing functionalities that work in a cooperative way to offer services. Smart buildings, self-driving cars, house monitoring and management, city electricity and pollution monitoring are some examples where IoT systems have been already deployed. Amongst different kinds of devices in IoT, cameras play a vital role, since they can capture rich and resourceful content. However, since multiple IoT devices share the same gateway, the data that is produced from high definition cameras congest the network and deplete the available computational resources resulting in Quality-of-Service degradation corresponding to the visual content. In this thesis, we present an edge-based resource management framework for serving video processing applications in an Internet-of-Things (IoT) environment. In order to support the computational demands of latency-sensitive video applications and utilize effectively the available network resources, we employ edge-based resource management policy. We evaluate our proposed framework with a face recognition use case.
3

A Fuzzy Logic Based Controller to Provide End-To-End Congestion Control for Streaming Media Applications

Pavlick, Bay 05 July 2005 (has links)
The stability of the Internet is at risk if the amount of voice and video traffic continues to increase at the current pace. While current transport layer protocols do work well for most applications, they still present some problems. TCP is reliable, tracks the state of some network conditions and reacts drastically to an indication of congestion. TCP serves data-oriented applications very well but it can lead to unacceptably low quality for streaming applications by multiplicatively reducing the congestion window upon a sign of congestion. The other main transport layer protocol, UDP, provides good service for streaming applications but is not friendly to TCP and can cause the well-known existing congestion collapse problem in the Internet. This thesis proposes a new protocol to provide a good service for voice and video applications while being friendly to TCP and solving the congestion collapse problem. The protocol utilizes a fuzzy logic controller that considers network related information to govern the applications sending rate while satisfying the users needs. Using network information such as the available bandwidth, Packet Loss Rates (PLR), and Round Trip Times (RTT) a fuzzy inference system optimizes the applications send rate to meet the requested rate in a smooth manner without wasting network resources unnecessarily. The fuzzy logic controller is designed and its performance evaluated using MATLAB model simulations. The results indicate that the fuzzy controller solves the congestion collapse problem by reducing the number of undelivered packets into the network by nearly 100%. It provides smooth transition changes as demonstrated by the controlled UDP flow utilizing an estimated 44% more of the available bandwidth to smooth the send rate than the TCP flow in a highly varying bandwidth environment. The controller also remains friendly with TCP which was demonstrated to share the bandwidth at nearly 50% with one other competing controlled UDP flow.
4

Mobilní aplikace pro pořizování a prohlížení fotografií stejného objektu v různých časech / Mobile App For Capturing and Viewing Photographs of the Same Object at Different Times

Plšek, Dominik January 2019 (has links)
Rephotography has been a popular research topic in the photography field for a long time. The purpose of rephotography itself is to repeatedly take photographs of the same scene at a different time. As a result, the sequence of rephotographs with the reference, often historical, the picture provides a compelling visualization of the evolution of the subject or capture its changes in time. However, the act of rephotography is difficult for the rephotographers as they have to cope with the ambiguous motions in six degrees of freedom and with the changes of the subject itself or its surrounding environment.        This thesis aims to create a mobile application that would help its users to capture a rephotograph more accurately and allow them to share the scenes amongst other users. The designed application uses available on-device sensors to navigate the user to the location and guide the user during the rephotography process to capture a precise rephotograph. Furthermore, the application contains user interface elements designed explicitly for rephotography. Moreover, the work describes topics about user interface design, iOS application development, and designing and deploying backend API for the mobile application.

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