Smartphones and tablets have been growing in popularity. These ultra mobile devices bring in new challenges for efficient network operations because of their mobility, resource constraints and richness of features. There is thus an increasing need to adapt network protocols to these devices and the traffic demands on wireless service providers. This dissertation focuses on identifying design limitations in existing network protocols when operating in ultra mobile environments and developing algorithmic solutions for the same. Our work comprises of three components. The first component identifies the shortcomings of TCP flow control algorithm when operating on resource constrained smartphones and tablets. We then propose an Adaptive Flow Control (AFC) algorithm for TCP that relies not just on the available buffer space but also on the application read-rate at the receiver. The second component of this work looks at network deduplication for mobile devices. With traditional network deduplication (dedup), the dedup source uses only the portion of the cache at the dedup destination that it is aware of. We argue in this work that in a mobile environment, the dedup destination (say the mobile) could have accumulated a much larger cache than what the current dedup source is aware of. In this context, we propose Asymmetric caching, a solution which allows the dedup destination to selectively feedback appropriate portions of its cache to the dedup source with the intent of improving the redundancy elimination efficiency. The third and final component focuses on leveraging network heterogeneity for prefetching on mobile devices. Our analysis of browser history of 24 iPhone users show that URLs do not repeat exactly. Users do show a lot of repetition in the domains they visit but not the particular URL. Additionally, mobile users access web content over diverse network technologies: WiFi and cellular (3G/4G). While data is unlimited over WiFi, users typically have monthly limits on data over the cellular network. In this context, we propose Precog, an action-based prefetching solution to reduce cellular data footprint on smartphones and tablets.

This thesis describes a universal multimedia access system and its implementation details. In the context of this thesis, universal multimedia access means accessing multimedia content over ubiquitous computer networks, using different computing platforms. The computer networks involve both wired and wireless networks, and computing platforms involve wired PC&rsquo / s, mobile PC&rsquo / s and personal digital assistants (PDA). The system is built on client/server architecture. Video data is H.263 coded and carried over RTP. Java Media Framework is utilized and its capabilities are extended with special plug-ins when necessary.

Nominally, one can expect any user of modern technology to at least carry a handheld device of the class of an iPAQ (perhaps in the form of a cellphone). The availability of technology in the environment (home, office, public spaces) also continues to grow at an amazing pace. With advances in technology, it is feasible to remain connected and enjoy services that we care about, be it entertainment, sports, or plain work, anytime anywhere. We need a system that supports seamless migration of services from handhelds to the environment (or vice versa) and between environments. Virtualization technology is able to support such a migration by providing a common virtualized interface on both source and destination. In this dissertation, we focus on two levels of virtualization to address issues for seamless mobility. We first identify three different kinds of spaces and three axes to support mobility in these spaces. Then we present two systems that address these dimensions from different perspectives. For middleware level virtualization, we built a system called MobiGo that can capture the application states and restore the service execution with saved states at the destination platform. It provides the architectural elements for efficiently managing different states in the different spaces. Evaluation suggested that the overhead of the system is relatively small and meets user's expectation. On the other hand, for device level virtualization, Chameleon is a Xen-like system level virtualization system to support device level migration and automatic capability adaptation at a lower level. Chameleon is able to capture and restore device states and automatically accommodate the heterogeneity of devices to provide the migration of services. Device level virtualization can address some issues that cannot be addressed in middleware level virtualization. It also has less requirements than middleware level virtualization in order to be applied to existing systems. Through performance measurements, we demonstrate that Chameleon introduces minimal overhead while providing capability adaptation and device state migration for seamless mobility in ubiquitous computing environments.

Mobile computing devices like handhelds are becoming ubiquitous and so is computing embedded in cyber-physical systems like cameras, smart sensors, vehicles, and many others. Further, the computation and communication resources present in these settings are becoming increasingly powerful. The resulting, rich execution platforms are enabling increasingly complex applications and system uses. These trends enable richer execution platforms for running ever more complex distributed applications. This thesis explores these opportunities (i) for cooperative mobile platforms, where the combined resources of multiple computing devices and the sensors attached to them can be shared to better address certain application needs, and (ii) for distributed platforms where opportunities for cooperation are further strengthened by virtualization. The latter offers efficient abstractions for device sharing and application migration that enable applications to operate across dynamically changing and heterogeneous systems without their explicit involvement. An important property of cooperative distributed platforms is that they jointly and cooperatively provide and maintain the collective resources needed by applications. Another property is that these platforms make decisions about the resources allocated to certain tasks in a decentralized fashion. In contrast to volunteer computing systems, however, cooperation implies the commitment of resources as well as the commitment to jointly managing them. The resulting technical challenges for the mobile environments on which this thesis is focused include coping with dynamic network topology, the runtime addition and removal of devices, and resource management issues that go beyond resource usage and scheduling to also include topics like energy consumption and battery drain. Platform and resource virtualization can provide important benefits to cooperative mobile platforms, the key one being the ability to hide from operating systems and applications the complexities implied by collective resource usage. To realize this opportunity, this thesis extends current techniques for device access and sharing in virtualized systems, particularly to improve their flexibility in terms of their ability to make the implementation choices needed for efficient service provision and realization in the mobile and embedded systems targeted by this work. Specifically, we use middleware-based approaches to flexibly extend device and service implementations across cooperative and virtualized mobile platforms. First, for cooperating platforms, application-specific overlay networks are constructed and managed in response to dynamics at the application level and in the underlying infrastructure. When virtualizing these platforms, these same middleware techniques are shown capable of providing uniform services to applications despite platform heterogeneity and dynamics. The approach is shown useful for sharing and remotely accessing devices and services, and for device emulation in mobile settings.

Miniaturization and functionality have always governed advances in electronic system technology. To truly achieve the goal of a multi mega-functional system, advances must be made not just at the IC level, but at the system level too. This concept of tighter integration at the system level is called System-on-Package (SOP). While SOP has a wide range of applications, this work targets the mobile application space. The main driver in the mobile application space is package profile. Reduction in thickness is very critical for enabling next-generation ultra-high density mobile products. In order to pack more functionality into a smaller volume, it is absolutely imperative that package profiles are reduced. The NEMI roadmap projects that the package profile should be reduced to 200µm from the current 500µm by 2014. This work attempts to demonstrate the feasibility of ultra-thin substrates (<200µm) using a new advanced material system tailored for high-frequency mobile applications. The main barriers to adoption of thin substrates include processing challenges, concerns about via and through hole reliability and warpage. Each of these factors is studied and a full-fledged test vehicle built to demonstrate the reliability of thin substrates using the advanced low-loss RXP-4/RXP-1 material system. Finite element models are developed to provide an understanding of the factors that affect the reliability of these substrates. Finally, IC assembly is demonstrated on these substrates.

Recently, Mobile Ad Hoc Networks (MANETs) have enjoyed a dramatic rise in popularity as potential solutions to connectivity in environments where telecommunication infrastructure is not available. Traditionally, MANETs are assumed to be stand-alone networks which do not require assistance from fixed network infrastructure (e.g. a backbone network). Based on this assumption, routing protocols for MANETs have been designed to work in stand-alone mode. However, throughput and coverage requirements of future 4G all-IP systems may require integration of MANETs into these systems to enhance the flexibility and pervasiveness of the networks. The coverage of existing infrastructure networks (wireless LAN hot-spots of 3G networks) can be effectively extended by the relaying communications via ad hot network nodes (wireless routers). Also, the limited services available within MANET can be extended to a wider range through connecting of the MANET to the Internet infrastructure. To achieve this, effective solutions are needed to many existing challenges in integrating MANETs with the Internet. / In this thesis, we propose solutions to three major challenges of interconnecting MANETs with the Internet. The underlying research problems can be listed as follows: Architecture options for integrating Mobile IP-based MANETs to the Internet via multiple gateways; The Internet extensions to reactive ad hoc routing protocols; Schemes for gateway discovery / Handoff in MANETs. / Thesis (PhDTelecommunications)--University of South Australia, 2007.

Zugl.: Saarbrücken, Univ., Diss., 2006

Thesis (Ph.D.)--University of Waikato, 2007. / Title from PDF cover (viewed February 29, 2008) Includes bibliographical references (p. 149-160)

Thesis (Ph.D.) -- University of Western Sydney, 2004. / A thesis submitted in fulfillment of the requirements for the degree of Doctor of Philosophy (Science) - Computing and Information Technology. Includes bibliography.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (p. 149-157).