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Live network multimedia applications (e.g., video conferencing, TV on demand) have been very popular in recent years and are expected to dominate Internet traffic in the near future. With multimedia and Internet-enabled devices being ubiquitous, mechanisms that ensure multimedia flows do not congest the Internet are crucial components of multimedia systems that are embraced rather than opposed by network service providers. The emergence of browser-based multimedia conferencing applications using the WebRTC protocol, an open source project aiming at Real-Time Communication (RTC) with Web, and wide deployment of these applications are expected to increase the traffic of interactive real-time multimedia on the Internet. RTP Media Congestion Avoidance Technique (RMCAT) may be applied to WebRTC, but this is a long-term process and WebRTC deployments will occur before RMCAT is completed. New methods and quick solutions are therefore required to protect the network from uncontrolled media flows until deployment of effective congestion control can be guaranteed. The RTP Protocol Circuit Breaker (RTP-CB) has been proposed in March 2012 within the Internet Engineering Task Force (IETF). Rather than providing congestion control, the RTP-CB is designed only to protect the network by terminating RTP/UDP flows that cause excessive congestion. While the deployment of congestion control for RTP/UDP flow remains an open issue, design a RTP-CB as a quick solution for protecting the current internet is the main focus of this work. In this work by analysing the UDP traffic over a limited path, a RTP-CB algorithm is designed. Then a packet sniffer's code (C routine) is written to sniff and analyse all RTP/UDP, TCP, RTCP SR, and RTCP RR traffic. Based on the designed algorithm the above code was developed further to work as a RTP-CB. This RTP-CB can be deployed on receiver or sender. After deployment of RTP-CB for RTP/UDP flows in a controlled network, its performance in a range of scenarios with using only its congestion rule has been evaluated. The evaluation showed some short coming in performance of RTP-CB in some certain condition when RTP-CB used only congestion rule. The performance of the RTP-CB is evaluated from two perspectives: First, the thesis considered network performance metrics, such as the frequency at which a RTP circuit breaker triggered. Then, it considered the experience of multimedia users, accounting for all outcomes to all users: those congesting the network (where the flow is terminated), those that did not (and are rewarded by reduced congestion) as well as flows that, without severely congesting the network, obtained little quality from a multimedia session and consumed network resources to no avail. Building on the knowledge gathered in these experiments, some extensions (Media Usability Rule) to the RTP-CB rules is proposed and evaluated. This work demonstrates this evaluation by streaming video flows over IP networks using a dedicated test-bed and proposed RTP-CB. These experiments assess the effect of network conditions (packet loss, jitter and network capacity constraint) on the transmission of different types of video stream with and without the proposed RTP-CB Media usability rule. The experiments prove that RTP-CB implementing the congestion rule alone can offer adequate protection to a network, but it does not perform well in some conditions, for example, when the bottleneck buffer size is small. Experiments confirm that the proposed (computationally inexpensive) modifications to the RTP-CB rules improve the RTP-CB performance. The results of these experiments and media usability rule were introduced in IETF RTP-CB draft version 07 of October 27, 2014 and later versions acknowledged contributions by the author of this thesis.

Master of Science in Engineering - Engineering / The next generation telecommunication networks offers traditional voice type services as well as advanced data services, typically of the multi-media based type, on top of an open resource, heterogeneous network that delivers services with a specified level of quality of service (QoS). The need for a comprehensive telecommunications service accounting management system in the such Next Generation Network is envisaged as the traditional telecommunications billing system does not meet the accounting management requirements in such network. This report present the design and implementation of a service accounting management system based on the Telecommunications Information Networking Architecture (TINA). The service accounting management in TINA service environment, which allows the users to obtain multiple service with specified network connection QoS, is emonstrated on the South Africa TINA Trial platform, which provides a next generation service environment conceived by TINA. This work shows the generation and the flow of the service and network usage accounting information in the distributed processing environment.

Telcos are adapting their business to address the rapid changing technology landscape (Moodley and van Olst 2011). Telcos require a flexible architecture to allow seamless adaptation and to leverage these new technologies to gain a competitive advantage (Moodley and van Olst 2011). This research is focused on the transport stratum as an extension to the OSA/Parlay gateway. The proposed OSA/Parlay Network Architecture and Interface has been designed. The OSA/Parlay Network Interface is characterised by openness, simplicity, API based, QoS support and technology independence. The OSA/Parlay Network Architecture features simplicity, technology independence, QoS mechanisms; call admission control; intelligent routing and supporting both federation of telcos and interoperation of legacy technologies. The OSA/Parlay Network Architecture and Interface has been demonstrated over a Java based Distributed Processing Environment (DPE) using CORBA. These architectural concepts and principles are demonstrated in a simulated environment and illustrate the Next Generation Network architectural characteristics. The research contribution therefore achieves an open architecture allowing for 3rd party application developers while also ensuring that call and service requests are provisioned end-to-end with guaranteed application level QoS in the transport network. The OSA/Parlay Network Architecture and Network Interface is synthesised from existing architectural standards and provides the following benefits. It is an extension of the OSA/Parlay standard by including the OSA/Parlay Network Architecture and Network Interface realises the OSA/Parlay next generation network. Both the OSA/Parlay Network Interface and the Network Architecture is specified in a technology agnostic manner. This ensures that the architecture remains future proof as it is not reliant on any particular technology. The long sought after Application level QoS is integrated into the architecture. The periodic network state updates inform the central Connection Coordinator object of both topological network changes as well as current performance of the constituent parts of the network. Intelligent routing of connections is achieved by adapting the Dijkstra algorithm to compute the best path based on dynamic network performance and is tested against QoS requirements, while the call admission control decision naturally allows for load balancing of connection paths within the network. This QoS mechanism achieves the goal of guaranteed QoS for a call admitted into the network.

Thesis advisor: Frank Gollop / By November 2003, wireless telecommunications operators were required by the FCC to have implemented wireless number portability. The FCC and the media claimed that this decrease in the cost of switching would force operators to react competitively by either decreasing prices or increasing the services offered at the same price to prevent customers from migrating to competitors. This paper empirically analyzes the effect that this regulation had on plan prices offered by the top four U.S. cellular operators over the period of Q2 2002 through Q2 2008, identifying whether they increased or decreased and by how much. This paper concludes that three out of the four nationwide carriers lowered prices in response to the implementation of wireless number portability. / Thesis (BA) — Boston College, 2013. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Economics Honors Program. / Discipline: College Honors Program. / Discipline: Economics.

Three families of fluorinated ligands based on benzothiazole derivatives, including 2-(2-hydroxyphenyl)benzothiazoles, bis(benzothiazolyl)amines and N-benzothiazol- 2-yl-methanesulfonamides, have been synthesised with different locations and extents of fluorination. Zinc complexes of the fluorinated 2-(2-hydroxyphenyl)benzothiazoles and bis(benzothiazolyl)amines have been successfully prepared. Crystallographic characterisations of these zinc complexes have revealed various molecular packing behaviours in their crystals in terms of πH-πH, πH-πF and πF-πF stacking under the influence of partial and complete fluorination. DFT calculations and photophysical studies of these complexes have demonstrated that fluorination of these molecules decreases their HOMO and LUMO levels simultaneously by about the same amount, roughly 0.1 eV per substitution of hydrogen by a fluorine atom. An inverse correlation has been found between the dihedral angles of conjugating aromatic rings and the photoluminescence full width at half maximum (FWHM), which could be one of the reasons for the broadening of photoluminescence spectra upon fluorination. The applications of the zinc complex of 2-(2-hydroxy-3,4,5,6- tetrafluorophenyl)-4,5,6,7-tetrafluorobenzothizole (Zn(F-BTZ)2) in organic light emitting diode (OLEDs) have been investigated. The electroluminescence of Zn(F-BTZ)2 has shown remarkable phosphorescence in the red region, indicating enhanced spin mixing and intersystem crossing introduced by the substitution of the hydrogen atoms by the higher atomic number fluorine atoms. This ability of providing a large population of triplets, together with the lack of CH or OH oscillators of this perfluorinated Zn(F-BTZ)2 molecule, allowed its use as an efficient chromophore to sensitise the erbium ions in a long-lifetime erbium complex, erbium (III) tris (pentafluorophenyl)imidodiphosphinate (Er(FTPIP)3). By doping Er(FTPIP)3 into Zn(F-BTZ)2 in the OLED, we achieved significant and long-lifetime emission from erbium at the important telecommunication wavelength of 1.5 μm.

Hui Shui Cheung. / Thesis submitted in: August 2005. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 37-38). / Abstracts in English and Chinese. / Acknowledgement --- p.i / Abstract --- p.ii / 摘要 --- p.iii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Related Work --- p.4 / Chapter Chapter 3 --- Single-Source Bandwidth Availability --- p.6 / Chapter 3.1 --- Measurement Methodology --- p.6 / Chapter 3.2 --- Measurement Results --- p.7 / Chapter Chapter 4 --- Multi-Souce Bandwidth Availability --- p.9 / Chapter 4.1 --- Correlation Among Senders --- p.9 / Chapter 4.2 --- Aggregate Bandwidth --- p.10 / Chapter 4.3 --- Sensitivity Analysis --- p.11 / Chapter Chapter 5 --- The Measurement System --- p.15 / Chapter 5.1 --- Overview of PlanetLab --- p.15 / Chapter 5.2 --- Measurement Tool --- p.16 / Chapter 5.3 --- Process Control --- p.17 / Chapter Chapter 6 --- Hybrid-Download Streaming --- p.21 / Chapter 6.1 --- Introduction --- p.21 / Chapter 6.2 --- Streaming Algorithm --- p.22 / Chapter 6.3 --- Performance Evaluation --- p.23 / Chapter Chapter 7 --- Playback-Adaptive Streaming --- p.26 / Chapter 7.1 --- Introduction --- p.26 / Chapter 7.2 --- Streaming Algorithm --- p.27 / Chapter 7.3 --- Adaptive Rebuffering Algorithm --- p.30 / Chapter 7.4 --- Performance Evaluation --- p.31 / Chapter Chapter 8 --- Conclusion --- p.36 / Bibliography --- p.37

Lam Ling Shun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 75-76). / Abstracts in English and Chinese. / Acknowledgement --- p.i / Abstract --- p.ii / 摘要 --- p.iii / Chapter Part I - --- A Transparent Rate Adaptation Algorithm for Streaming Video Over The Internet --- p.1 / Chapter Chapter 1 --- Introduction --- p.2 / Chapter Chapter 2 --- Related Work --- p.5 / Chapter Chapter 3 --- System Model --- p.8 / Chapter Chapter 4 --- Client Buffer Occupancy and Network Bandwidth Estimation --- p.12 / Chapter Chapter 5 --- Rate Adaptation --- p.16 / Chapter 5.1 --- Segment-based Rate Control --- p.16 / Chapter 5.2 --- Preemptive Rate Control --- p.18 / Chapter Chapter 6 --- Performance Evaluation --- p.20 / Chapter 6.1 --- Sensitivity to Prefetch Duration --- p.22 / Chapter 6.2 --- Effectiveness of Preemptive Rate Control --- p.24 / Chapter 6.3 --- Comparison with the CR algorithm --- p.25 / Chapter Chapter 7 --- Conclusions --- p.28 / Bibliography --- p.29 / Chapter Part II - --- Buddy-TCP - A Sender-driven Algorithm for Bandwidth Reallocation Among TCP Flows --- p.31 / Chapter Chapter 1 --- Introduction --- p.32 / Chapter Chapter 2 --- Background --- p.36 / Chapter 2.1 --- Flow Control --- p.36 / Chapter 2.2 --- Congestion Control --- p.37 / Chapter Chapter 3 --- Buddy-TCP --- p.39 / Chapter 3.1 --- Sender Protocol Stack --- p.39 / Chapter 3.2 --- Joint Congestion Window Update --- p.42 / Chapter Chapter 4 --- Performance Study --- p.47 / Chapter 4.1 --- Performance Metrics --- p.48 / Chapter 4.2 --- Bandwidth Allocation Accuracy --- p.50 / Chapter 4.3 --- Impact on Ordinary TCP Flows --- p.52 / Chapter 4.4 --- Effect of Heterogeneous RTTs --- p.55 / Chapter 4.5 --- Effect of Random Packet Loss --- p.58 / Chapter 4.6 --- Effect of TCP SACK --- p.62 / Chapter 4.7 --- Effect of Abrupt Link Congestion --- p.64 / Chapter 4.8 --- Convergence --- p.66 / Chapter Chapter 5 --- Implementation and Experimental Results --- p.68 / Chapter 5.1 --- Implementation --- p.68 / Chapter 5.2 --- Experimental Results --- p.69 / Chapter Chapter 6 --- Conclusions --- p.73 / Bibliography --- p.75