Video dissemination capabilities are crucial for the deployment of many services over VANETs. These services range from enhancing safety via the dissemination of video from the scene of an accident, to advertisement of local services or businesses. This work considers the infrastructure-less scenario of VANETs and dissemination of video content over this network environment, which is extremely challenging mainly due to its dynamic topology and stringent requirements for video streaming. This study discusses issues and challenges that need to be tackled for disseminating high-quality video over VANETs. Furthermore it surveys and analyzes the suitability of different existing solutions aimed towards effective and efficient techniques for video dissemination in vehicular networks. As a result, a set of the most promising techniques are selected, described in detail and evaluated based on standard terms in quality of service. This thesis also discusses efficiency and suitability of these techniques for video dissemination and compares their performance over the same network condition. In addition, a detailed study on the effect of network coding on video dissemination protocols has been conducted to guide how to employ this technique properly for video streaming over VANETs. From this study, a summary of the observations was obtained and used to design a new hybrid solution by deploying robust and efficient techniques in number of existing protocols in an optimal manner. The proposed hybrid video dissemination protocol outperforms other protocols in term of delivery ratio and complies with other quality-of-service requirements for video broadcasting over vehicular environments.

Vehicular Ad Hoc Networks (VANETs) are no longer a futuristic promise but rather an attainable technology. Vehicles are already equipped with a variety of computational devices that control or assist drivers in many tasks such as localization, safely breaking, parking and passengers entertainment. The majority of services envisioned for VANETs either require the provision of multimedia support or have it as an extremely beneficial additional feature. In particular, video streaming capabilities over VANETs are crucial to the development of interesting and valuable services. However,VANETs’ highly dynamic topology poses as a demanding challenge to the fulfillment of video streaming’s stringent requirements. The main goal on this thesis is the development of feasible solutions that support the streaming of video content over VANETs. Initially, the main issues of VANETs are explained through both a discussion of its characteristics and the results of some preliminary conclusions. Based on this understanding of VANETs’ peculiarities, three distinguishing solutions are designed REACT-DIS, REDEC and VIRTUS; the two first for video dissemination and the later for video unicast. These solutions offer a great advancement towards the provision of video streaming capabilities but packet loss is still an issue at high data rates. In order to improve the delivery ratios reached by the previous solutions, redundancy is used as an error correction mechanism. The use of redundancy is ideal for VANETs in handling packet loss as they do not require any interaction between source and receivers nodes. Sophisticated coding techniques were used for an efficient use of the increase on entropy of the information sent by the source node. It was also evaluated the selective use of redundancy solely on packets carrying the crucial information of I-frames. Although this selective approach obtained lower overall delivery ratios than when redundancy is used for all packets, the video quality obtained similar improvements under a much lower cost. The evaluation on the use of redundancy has considered the impact on the rate by which unique video content is received at end-users which is fundamental to understand the resolution of videos that can be displayed. This thesis provides several contributions as it advances the knowledge in the peculiarities of VANETs, solutions for video streaming over VANETs and the use of redundancy as an error correction mechanism for video streaming over VANETs.

Video streaming over the Internet can be very difficult under the traditional client-server model. Peer-to-peer (P2P) systems, in which each participating peer contributes its upload bandwidth to other peers while it downloads data, have been successful in file-sharing applications, and they appear to be promising in delivering video contents, too. However, the existence of network address translation (NAT) is always considered as a challenge to peer-to-peer systems. NAT has been a practical solution to the Internet Protocol version 4 (IPv4) address exhaustion problem, as it reduces the usage of IP addresses by allowing multiple private hosts to share a single public IP address, but NAT can degrade the performance of a peer-to-peer system as it limits the direction of connectivity. Measurement studies show that a considerable fraction of peer-to-peer video streaming system users are behind NAT devices, and that their uplink bandwidth is not well utilized, but the literature lacks a quantitative analysis of the impact of NAT on the performance of P2P video streaming systems. In this thesis, an extensible analytical model is built to capture the performance for P2P live streaming systems with a certain percentage of users behind NAT and cannot be reached by NAT traversal techniques, the correctness of which is verified by software simulation. A simple mechanism is proposed in this thesis, which is able to effectively improve the system performance and fairness by counteracting the negative impact of NAT, and it can also be used to reduce the usage of server bandwidth. / Graduate

Thesis (M.S.)--University of Hawaii at Manoa, 2006. / Includes bibliographical references (leaves 61-63). / ix, 63 leaves, bound ill. 29 cm

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Internet Protocol multicast has been standardised since the late 1980's, but is yet to be extensively deployed by most Internet Service Providers. Many organisations are not willing to bear the additional router CPU load and memory requirements that multicast entails, and the IP multicast suite of protocols requires deployment on every router spanned by the multicast group to operate. Additionally, these protocols are predominantly designed for the general case of multiple-source, multiple-receiver transmission and can be complex and inefficient to use in simpler scenarios. Single-source streaming of multimedia on the Internet is rapidly becoming a very popular application, and is predominantly being served by content providers using simultaneous unicast streams. A multicast transmission protocol designed for this application that can operate without requiring a widely deployed IP multicast infrastructure has the potential to save content-providers and network service providers significant amounts of bandwidth. This protocol should provide packet duplication and forwarding capabilities on routers in the network, rather than pushing this functionality to the receivers themselves, requiring them to become part of the multicast infrastructure. We describe Lorikeet, a new protocol for the multicast distribution of multimedia streams from a single source. This protocol builds its multicast tree from the source, discovering routers that support the protocol in the network and using them to provide branching in the tree. The tree itself is managed in a decentralised fashion, with joining receivers finding parent routers through a limited, recursive search of the tree. On a participating node, information about the tree's structure is limited to the addresses of that node's children and its path through the tree back to the source. Unlike most other multicast protocols, a new receiver is connected to the tree using its forward path from the source and packets are delivered through the tree via hop-by-hop delivery over unicast connections between nodes. Lorikeet also actively maintains the tree structure using a localised rearrangement algorithm triggered by a topological change in the tree structure. This rearrangement allows the tree to remain efficient in the face of changes to the receiver population, which can change the shape of the tree over time. Lorikeet is designed to operate with no further protocol support than that provided by existing Internet unicast protocols. It requires none of the standard IP multicast infrastructure, such as Class D group addressing. Its use of unicast connections between nodes allows it to be deployed incrementa.lly on the network, and its behaviour will degrade to simultaneous unicast when no routers that support the protocol are present at all. However, significant performance gains can be achieved even when there are only a few supporting routers present in the network: Lorikeet produces trees with half the cost of a unicast tree when just 10% of routers are Lorikeet-capable. Lorikeet's tree construction and rearrangement algorithms generate multicast trees of comparable total cost to those created by algorithms of considerably higher message complexity, such as those that employ exhaustive searches of the tree during joins. We develop the Lorikeet protocol from a set of requirements based on its target application and the properties of the current Internet. After describing the protocol's behaviour, we analyse its message complexity and its performance in terms of tree cost. We also analyse several other multicast protocols from the research literature, comparing their performance to that of Lorikeet in both complete deployment and incremental deployment scenarios. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1283785 / Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2007

The semiconductor industry has seen a paradigm shift from Application Specific Integrated Circuits to Multiprocessor System on Chip systems over the last decade, primarily due to the miniaturization of the transistor. However, billion of transistors available on a single chip need to be used efficiently to provide more functionalities in portable devices, yet minimize power and chip area, which increases the design complexity of multiprocessor systems. Tighter time to market deadlines further pressurizes the designer, requiring a comprehensive automation of the design process of such complex multiprocessor systems. This thesis presents a design automation methodology for the design of Multiprocessor System on Chip (MPSoC) systems for multimedia applications. This thesis introduces a heterogeneous multiprocessor system where processing elements are connected in a pipelined fashion. A multimedia application is executed very efficiently on a pipelined system due to the stream oriented data flow nature of such applications. Application Specific Instruction set Processors (ASIPs) are used as the elementary processing elements in the multiprocessor system as they can be customized according to the application tasks assigned to them. The problem of selecting a processor configuration for each of the ASIPs in the pipelined system is formalized. We present three different techniques to select processor configurations by exploring the design space of an ASIP based pipelined system, and integrating them into a flexible and designer driven design flow for efficient exploration of large design spaces in order of 10^16 design points. The first two techniques are based on Integer Linear Programming (ILP), named Exact ILP formulation (EIF) and Reduced ILP formulation (RIF), while the third technique is based on a novel heuristic. We also developed a design space pruning algorithm that can enable the use of EIF and RIF to obtain optimal or near optimal design points from large design spaces. For four multimedia applications, we show that RIF and the heuristic can explore the design space and reveal the Pareto front in several hours, while EIF took several days to obtain the Pareto front. The quick availability of the Pareto front of a design space will help the designer to make early changes in the design. Furthermore, it is shown that, on average, the error incurred by RIF and the heuristic is within 1.25% and 2.25% of the optimal design points obtained via EIF for all the four multimedia applications. In the worst case, RIF introduced an error of 17.08% while the heuristic had an error of 11.39%.

Thesis (Ph.D.)--George Mason University, 2008. / Vita: p. 141. Thesis director: Edward J. Wegman. Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Computational Sciences and Informatics. Title from PDF t.p. (viewed July 3, 2008). Includes bibliographical references (p. 105-110). Also issued in print.

Thesis (M.Sc. (Computing Sc.)) - Simon Fraser University, 2004. / Theses (School of Computing Science) / Simon Fraser University.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: reordering predicates; multi-join operator; sliding windows; window predicates; join algorithm; continuous queries. Includes bibliographical references (p. 101-103).

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Margarida F. Jacome. Vita. Includes bibliographical references.