Access networks have been going through many reformations to make them adapt to arising traffic trends and become better suited for many new demanding applications. To that end, incorporating fog and edge computing has become a necessity for supporting many emerging applications as well as alleviating network congestions. At the same time, energy-efficiency has become a strong imperative for access networks to reduce both their operating costs and carbon footprint. In this dissertation, we address these two challenges in long-reach optical access networks. We first study the integration of fog and edge computing with optical access networks, which is believed to form a highly capable access network by combining the huge fiber capacity with closer-to-the-edge computing and storage resources. In our study, we examine the offloading performance under different cloudlet placements when the underlying bandwidth allocation is either centralized or decentralized. We combine between analytical modeling and simulation results in order to identify the different factors that affect the offloading performance within each paradigm. To address the energy efficiency requirement, we introduce novel enhancements and modifications to both allocation paradigms that aim to enhance their network performance while conserving energy. We consider this work to be one of the first to explore the integration of fog and edge computing with optical access networks from both bandwidth allocation and energy efficiency perspectives in order to identify which allocation paradigm would be able to meet the requirements of next-generation access networks.

Due to its ubiquitous availability, Short Message Service (SMS), first introduced in the 1980s, became not only the most popular way of communication, but also stimulated the development of SMS-based value added services. This application-to-person traffic is delivered to end users through SMS aggregators who provide the link between service providers and mobile carriers. In order to perform optimal traffic routing, the aggregators need to estimate the quality of each potential international route to the specified destination. The evaluation criteria include end-to-end delivery time, as well as correct verification of delivered data. This thesis suggests a method of quality of service (QoS) assessment for international SMS service which combines two types of tests, end-to-end delay measurements and various verification tests. A prototype of the testing system for international SMS service was developed to generate SMS traffic, collect and analyze results, and evaluate the experienced QoS of the SMS route used in accordance with the proposed approach. As a part of end-to- end delay measurement tests, SMS traffic was sent to Singtel network in Singapore along two routes. The verification tests were executed via different routes to two mobile networks: Singtel and Tele2 (Sweden). The results of the performed measurements determined the route with the highest QoS, i.e. the one with bigger bottleneck bandwidth and lower data loss rate. The prototype of the SMS testing system can be used by SMS aggregators to verify delivery of a SMS message, check the integrity of the message, figure out interconnection type of the route supplier with the destination carrier and to identify the presence of load balancers in the path. The prototype also makes it possible to compare end-to-end delay times of several routes and compute bottleneck values for each of the tested routes.

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With the rise of wireless sensor networks and the internet of things, many sensors are being developed to help us monitor our environment. Sensor applications from marine animal tracking to implantable healthcare monitoring require small and non-invasive methods of powering, for which purpose traditional batteries are considered too bulky and unreasonable. If appropriately designed, energy harvesting devices can be a viable solution. Solar and wind energy are good candidates of power but require constant exposure to their sources, which may not be feasible for in-vivo and underwater applications. Mechanical energy, however, is available underwater (the motion of the waves) and inside our bodies (the beating of the heart). These vibrations are normally low in frequency and amplitude, thus resulting in a low voltage once converted into electrical signals using conventional mechanical harvesters. These mechanical harvesters also suffer from narrow bandwidth, which limits their efficient operation to a small range of frequencies. Thus, there is a need for a mechanical energy harvester to convert mechanical energy into electrical energy with enhanced output voltage and for a wide range of frequencies. In this thesis, a new mechanical harvester is introduced, and two different methods of rectifying it are investigated. The designed harvester enhances the output voltage and extends the bandwidth of operation using a mechanical frequency up-convertor. This is implemented using magnetic forces to convert low-frequency vibrations to high-frequency pulses with the help of a piezoelectric material to generate high output voltage. The results show a 48.9% increase in the output voltage at 12.2Hz at an acceleration of 1.0g, and a bandwidth increase from 0.23Hz to 11.4Hz. For the rectification, mechanical rectifiers are discussed, which would obviate the need for electrical rectification, thus preventing the losses normally caused by the threshold voltage of electronics. Two designs of mechanical rectifiers are investigated and implemented on the frequency up-converter: a static rectifier and a rotating rectifier. The results show a voltage rectification, which required a sacrifice in the bandwidth and boosted voltage.

In the form of images and videos, visual content has always attracted considerable interest and attention to itself since the early days of the computer era. Although, due to the high density of information in such contents, it has always been challenging to generate, process and broadcast videos and images. These challenges grew along with the demand for higher quality content and attained the research community's attention to themselves. Even though many works have been done by researchers and engineers in academic and industrial environments, the demand for high-quality content introduces new constraints on the quality, performance (speed) and energy consumption. This thesis focuses on a couple of image and video processing applications and introduces new approaches and tweaks to improve the performance and save resources while keeping the functionality intact. In the first part, we target Interferometric Synthetic Aperture Radar (InSAR), an imaging technique used by satellites to capture the earth's surface. Many algorithms have been developed to extract useful information, such as height and displacement, from such images. However, the sheer size of these images, along with the complexity of most of these algorithms, lead to very long processing time and resource utilization. In this work, we take one of the dominant algorithms used for almost every In-SAR application, Phase Unwrapping, and introduce an approach to gain up to 6.5 times speedups. We evaluated our method on InSAR images taken by the Radarsat-2 sensor and showed its impact on a real-world application. In the second part of this thesis, we look at a prevalent application, video streaming. These days video streaming dominates the internet traffic, so any slight improvement in terms of energy consumption or resource utilization will make a sizable difference. Although the streamers use various encoding techniques, the quality of experience of the clients prevents them from overplaying these techniques. On the other hand, there has been a growing interest in another venture of research which focuses on developing techniques that aim to restore the quality of the videos that have been subjected to compression. Although these techniques are used by many users on the receiver side, the streamers often ignore their capabilities. In our work, we introduce an approach that makes the streamer aware of the capabilities of the receiver and utilizes that awareness to reduce the cost of transmission without compromising the end user's quality of experience. We demonstrated the technique and proved our concept by applying it to the HEVC encoding standard and JCT-VC dataset. / Graduate

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Because broadband wireless systems benefit from accurate channel characterization, there is growing interest in broadband wireless multiple-input multiple-output (MIMO) channel models. This thesis verifies the suitability of the Saleh Valenzuela with Angle (SVA) model for wideband MIMO communication models. While recent wideband MIMO measurements have been obtained by switching a single transmit/receive pair over all possible antenna pair combinations, a simultaneous probing system is superior because of the time required for the antenna-switching channel measurements. This work provides two different wideband channel estimation algorithms based on simultaneous transmission from and reception on all antennas. Simulated data from an electromagnetic ray tracing tool is used (as a substitute for measured data) to obtain propagation data. One of the wideband estimation algorithms is then used to extract MIMO channel data from propagation data. From these estimated channels, parameters such as capacity, coherence bandwidth, RMS delay spread and maximum delay spread are compared (statistically) to those obtained from the SVA model. The comparisons of the different parameters show the ability of the SVA model to simulate wideband MIMO communication channels.

A need for high bandwidth operational amplifiers, or op-amps, exists for certain applications. This need requires research in the area of op-amp bandwidth extension. The proposed method of this thesis uses Negative Capacitance Generation (NCG), which involves using the Miller effect to generate an equivalent negative capacitance at a given node in a circuit, to extend the bandwidth of an op-amp. This is accomplished by first applying NCG to the second stage of an op-amp, in which the op-amp has been compensated using Single Capacitor Miller Compensation (SCMC). Next, the Miller capacitor used to compensate the op-amp can be reduced and thus, the bandwidth of the op-amp is extended. The proposed method employed a 100dB, classic two-stage op-amp with a 7.7MHz gain-bandwidth product (GBW). It was discovered that after applying NCG to several places in the op-amp besides the second stage that the GBW was roughly doubled. The GBW of the second stage was improved by a factor of 9.3. This discrepancy in GBW improvements was researched and certain barriers were discovered. Although the barriers were not eliminated, research in overcoming them and obtaining greater improvements in op-amp bandwidth is encouraging.

Current Massively Multi-player Online Games (MMOGs) have enormous server-side bandwidth requirements. The costs of providing this bandwidth is in turn passed on to the consumer in the form of high monthly subscription fees. Prior work has primarily focused on distributing this bandwidth using peer-to-peer architectures, but these architectures have difficulty preventing cheating, overwhelming low resource peers, and maintaining consistent game state. We have developed a hybrid game architecture that combines client-server and peer-to-peer technologies to prevent cheating, maintain centralized and consistent game state, significantly reduce central server bandwidth, and prevent lower capacity players from being overwhelmed. By dramatically reducing the bandwidth needed to host a game without introducing additional liabilities, our hybrid architecture reduces the costs associated with that bandwidth and allows MMOG developers to reduce the cost of monthly subscription fees. In addition, because the central server will need less bandwidth per player, a single server is able to support considerably more concurrent players. Our experiments show that bandwidth can be reduced by up to 95% and a single server can support a game twice as large.