Instantly Decodable Network Coding (IDNC) is a subclass of opportunistic network coding that has numerous desirable properties for a wide spectrum of applications, namely its faster decoding delay, simpler coding and decoding processes, and no decoding buffer requirements. Nonetheless, IDNC suffers from two main problems that may limit its attractiveness, as an implementable solution in future wireless networks, against full network coding (FNC), widely studied in the literature. First, it cannot guarantee the decoding of a new packet at each receiver in each transmission, which may severely affect its completion delay. Second, it requires full feedback in order to operate properly, which may be prohibitive for several practical network settings. In this thesis, we aim to reduce the effect of these drawbacks by studying the problems of minimizing the IDNC completion delay in full and limited feedback scenarios. Since completion delay cannot be optimized only through local decisions in each of the transmissions, we first study the evolution of the IDNC coding opportunities and determine the strategies maximizing them, not only for one transmission, but for all future transmissions. We then formulate the completion delay problem as a stochastic shortest path (SSP) problem, which turns out to be of extremely large dimensions that makes its optimal solution intractable. Nonetheless, we exploit the structure of this SSP and the evolution of the coding opportunities to design efficient algorithms, which outperform FNC in most multicast scenarios and achieve a near-optimal performance in broadcast scenarios. However, since FNC still outperforms IDNC in some network scenarios, we design an adaptive selection algorithm that efficiently selects, between these two schemes, the one that achieves the smaller completion delay. To study the effect of feedback reduction, we formulate the completion delay minimization problem, for the cases of intermittent and lossy feedback, as extended SSP and partially observable SSP problems, respectively. We show that these new formulations have the same structure of the original SSP. We thus extend the designed algorithms to operate in intermittent and lossy feedback scenarios, after taking update decisions on the attempted and un-acknowledged packets. These redesigned algorithms are shown to achieve tolerable degradation for relatively low feedback frequencies and high feedback loss rates.

Resource management –particularly power and spectrum management– is becoming increasingly important owing to the fast growing market of smart-phones and other power-hungry wireless devices. While WiFi and cellular communication accounts for a significant portion of the smart-phone power expenditure, spectrum is equally paramount and scarce as well. This demands for an efficient and judicious resource management schemes that is also viable in terms of the practical implementation and complexity. This thesis focuses on the various setups of multi-channel relaying system as an emerging wireless technology, and provides rate optimal, yet easy-to-implement, resource management solutions for them. We exploit the channel pairing (CP) capability of a multi-channel relay node in our design. This capability allows the relay to receive a signal from one channel and transmit a processed version of the signal on a different channel. CP jointly optimized with power allocation (PA), which determines each channel’s power, can lead to significant improvement in spectral efficiency. For two setups, namely multi-hop and multi-user setups, we present the total achievable rates through optimizing CP, PA and channel-user assignment which incurs multi-user diversity. While the achievable rates provide theoretical insight for the performance of such systems, we next incorporate the integer nature of bit loading and rate adaptation, and via an innovative optimization technique, we present the jointly optimal solution to the problem of bit loading, PA and CP.

The purpose of this thesis is to present a novel controller structure for scalable switch-mode power supplies targeting low power applications. The design employs masterless control, where each phase is responsible for its own control in a multiphase system. The controller is capable of automatically configuring itself to work with a single phase system or a multiphase system. The configuration process allows each controller to determine the number of phases in the system, as well as to synchronize and sequence the phases. With this architecture, the same controller design can be used in many types of applications requiring different numbers of phases, resulting in a decrease in cost and design effort. The proposed design has been verified experimentally on FPGA and IC implementations.

This thesis considers resource allocation to achieve the max-min fairness in a selection-based OFDM network wherein source nodes are assisted by fixed relays. Transmission strategy selection, relay assignment, and power allocation at the sources and relays are considered crucial in architecture design of such networks. However, this is a combinatorial problem with exponential complexity. In this thesis, we investigate two relaying scenarios, i.e., subcarrier-based and block-based relaying. In subcarrier-based relaying, all subcarriers are assumed to be independent transmissions while relays use decode-and-forward protocol. However, in addition to the synchronization problems caused, it is likely impractical for a relay to only decode a subset of subcarriers. This motivates a search for practical block-based schemes. We also propose a simple, decentralized, block-based relaying scheme. Simulation results using the COST-231 channel model reveals that this scheme has a close-to-optimal performance while offering computational benefits.

Bursts of femtosecond laser pulses with a repetition rate of 38.5MHz were created by integrating a purpose-built burst resonator system with a Ti: Sapphire laser system. The timing control system in this work provided flexibility for generation of any desirable pulse train profile in the burst envelope. These laser pulses further have been used for high aspect ratio hole drilling inside glass materials. High repetition rate of the pulses produces heat accumulation effects during the laser machining interaction which provided the possibility of deeper etching, increased the aspect ratio, and mitigated cracks and damages effects of single pulses. During the process, time-resolved nanosecond scale side-view images have been recorded with a time-gated intensified-CCD camera enabling the observation of transient effects during the laser machining process. These side-view images further have been used to assess the physics of burst interaction and illustrate benefits and disadvantages of high repetition rate laser pulses.

This thesis considers resource allocation to achieve the max-min fairness in a selection-based OFDM network wherein source nodes are assisted by fixed relays. Transmission strategy selection, relay assignment, and power allocation at the sources and relays are considered crucial in architecture design of such networks. However, this is a combinatorial problem with exponential complexity. In this thesis, we investigate two relaying scenarios, i.e., subcarrier-based and block-based relaying. In subcarrier-based relaying, all subcarriers are assumed to be independent transmissions while relays use decode-and-forward protocol. However, in addition to the synchronization problems caused, it is likely impractical for a relay to only decode a subset of subcarriers. This motivates a search for practical block-based schemes. We also propose a simple, decentralized, block-based relaying scheme. Simulation results using the COST-231 channel model reveals that this scheme has a close-to-optimal performance while offering computational benefits.

Bursts of femtosecond laser pulses with a repetition rate of 38.5MHz were created by integrating a purpose-built burst resonator system with a Ti: Sapphire laser system. The timing control system in this work provided flexibility for generation of any desirable pulse train profile in the burst envelope. These laser pulses further have been used for high aspect ratio hole drilling inside glass materials. High repetition rate of the pulses produces heat accumulation effects during the laser machining interaction which provided the possibility of deeper etching, increased the aspect ratio, and mitigated cracks and damages effects of single pulses. During the process, time-resolved nanosecond scale side-view images have been recorded with a time-gated intensified-CCD camera enabling the observation of transient effects during the laser machining process. These side-view images further have been used to assess the physics of burst interaction and illustrate benefits and disadvantages of high repetition rate laser pulses.

The purpose of this thesis is to present a novel controller structure for scalable switch-mode power supplies targeting low power applications. The design employs masterless control, where each phase is responsible for its own control in a multiphase system. The controller is capable of automatically configuring itself to work with a single phase system or a multiphase system. The configuration process allows each controller to determine the number of phases in the system, as well as to synchronize and sequence the phases. With this architecture, the same controller design can be used in many types of applications requiring different numbers of phases, resulting in a decrease in cost and design effort. The proposed design has been verified experimentally on FPGA and IC implementations.

Instantly Decodable Network Coding (IDNC) is a subclass of opportunistic network coding that has numerous desirable properties for a wide spectrum of applications, namely its faster decoding delay, simpler coding and decoding processes, and no decoding buffer requirements. Nonetheless, IDNC suffers from two main problems that may limit its attractiveness, as an implementable solution in future wireless networks, against full network coding (FNC), widely studied in the literature. First, it cannot guarantee the decoding of a new packet at each receiver in each transmission, which may severely affect its completion delay. Second, it requires full feedback in order to operate properly, which may be prohibitive for several practical network settings. In this thesis, we aim to reduce the effect of these drawbacks by studying the problems of minimizing the IDNC completion delay in full and limited feedback scenarios. Since completion delay cannot be optimized only through local decisions in each of the transmissions, we first study the evolution of the IDNC coding opportunities and determine the strategies maximizing them, not only for one transmission, but for all future transmissions. We then formulate the completion delay problem as a stochastic shortest path (SSP) problem, which turns out to be of extremely large dimensions that makes its optimal solution intractable. Nonetheless, we exploit the structure of this SSP and the evolution of the coding opportunities to design efficient algorithms, which outperform FNC in most multicast scenarios and achieve a near-optimal performance in broadcast scenarios. However, since FNC still outperforms IDNC in some network scenarios, we design an adaptive selection algorithm that efficiently selects, between these two schemes, the one that achieves the smaller completion delay. To study the effect of feedback reduction, we formulate the completion delay minimization problem, for the cases of intermittent and lossy feedback, as extended SSP and partially observable SSP problems, respectively. We show that these new formulations have the same structure of the original SSP. We thus extend the designed algorithms to operate in intermittent and lossy feedback scenarios, after taking update decisions on the attempted and un-acknowledged packets. These redesigned algorithms are shown to achieve tolerable degradation for relatively low feedback frequencies and high feedback loss rates.

Nanocrystal solids represent an exciting new class of materials. These are often referred to as artificial solids, in which the nanocrystals take the place of atoms in traditional solids. This thesis reports the utility of field-effect transistor measurements to elucidate charge transport parameters, such as charge carrier density and charge carrier mobility in a nanocrystal solid. The evolution of these parameters with chemical treatments is followed and correlated to improved performance in photovoltaic devices. Chemical treatments are demonstrated to simultaneously engineer interparticle spacing, doping and electronic coupling in nanocrystal solids. The nanocrystal solids are then utilized as building blocks for fabricating all nanocrystal heterostructure. A type-I nanocrystal heterostructure is fabricated to demonstrate efficient electroluminescent device in the infrared communications wavelength. The device emits at peak wavelength of 1.58 um with an effciency of 0.5%.