Engineering Commons^™

Spectrum Modeling Of Rf Amplifiers Based On Intercept Points With Measurement Improvements, Siyuan Yan

Dissertations and Theses

Orthogonal frequency-division multiplexing has been developed into a popular modulation scheme for wireless communication systems, used in applications such as LTE and 5G. In wireless communication system, spectrum regrowth caused by RF amplifiers will generate distortions to both passband in use and adjacent channels such that the transmission quality will be degraded. The study of this dissertation aims to predict the spectrum regrowth for OFDM based signals at the output of a RF amplifier due to the nonlinearity. Based on Taylor polynomial coefficients, a power spectrum expression for amplified OFDM signals in terms of intercept points up to nth-order is …

Power Efficiency Enhancement And Linearization Techniques For Power Amplifiers In Wireless Communications, Haider Al-Kanan

Dissertations and Theses

Wireless communication systems require Power Amplifiers (PAs) for signal transmissions. The trade-off between power efficiency and nonlinear distortion in PAs degrades the communication performance. Thus, power efficiency and nonlinearity are two main concerns of operating PAs in communication systems. Nonlinear behavioral models are typically used to quantify and mitigate the distortion effects of PAs on communication systems. This dissertation presents an estimation approach for modeling and linearizing the PA Amplitude-to-Amplitude (AM/AM) nonlinearity using the design specifications of PAs, such as gain, the third-order intercept point, and 1dB compression point. Furthermore, an enhanced approach for modeling solid-state power amplifiers is developed …

A Comparative Assessment Of Crowded Source Travel Time Estimates: A Case Study Of Bluetooth Vs Inrix On A Suburban Arterial, Fahad Fasha Alhajri

Civil and Environmental Engineering Master's Project Reports

Travel time is one of the most widely used measures of traffic performance monitoring for the transportation systems. It is a simple concept that refers to the time required to traverse between two points of interest. Travel time is communicated and used by a wide variety of audience such as commuters, media reporters, and transportation engineers and planners. Recent developments within the wireless communication area made it possible to collect travel time data at a relatively low cost. These emerging technologies include mobile phone based technologies, in-vehicle navigation technologies and automatic vehicle identification technologies. Although these technologies offer a great …

Design Of Radio-Frequency Filters And Oscillators In Deep-Submicron Cmos Technology, Haiqiao Xiao

Dissertations and Theses

Radio-frequency filters and oscillators are widely used in wireless communication and high-speed digital systems, and they are mostly built on passive integrated inductors, which occupy a relative large silicon area. This research attempted to implement filters and oscillators operating at 1-5 GHz using transistors only, to reduce the circuits’ area. The filters and oscillators are designed using active inductors, based on the gyrator principle; they are fabricated in standard digital CMOS technology to be compatible with logic circuits and further lower the cost. To obtain the highest operating frequency, only parasitic capacitors were used.

Two new active-inductor circuits are derived …

Distributed Cooperative Framework And Algorithms For Wireless Network Performance Optimization, Emily Hong Qi

Dissertations and Theses

In Wireless Local Access Networks (WLANs), the Medium Access Control (MAC) protocol is the primary element that determines the efficiency of sharing the limited communication bandwidth of the wireless channel. IEEE 802.11 MAC uses the contention-based Distributed Coordination Function (DCF) as a fundamental medium access mechanism. However, the dynamic nature of the wireless environment creates mobility challenges of maintaining maximum channel capacity, of obtaining optimal throughput and latency, and of retaining good security in a distributed wireless network.

This dissertation first introduces a set of parameters to characterize the medium status and radio environment, and a mechanism for mobile devices …

Analysis Of Relay-Based Cellular Systems, Ansuya Negi

Dissertations and Theses

Relays can be used in cellular systems to increase coverage as well as reduce the total power consumed by mobiles in a cell. This latter benefit is particularly useful for mobiles operating on a depleted battery. The relay can be a mobile, a car or any other device with the appropriate communication capabilities. In thesis we analyze the impact of using relays under different situations. We first consider the problem of reducing total power consumed in the system by employing relays intelligently. We find that in a simulated, fully random, mobile cellular network for CDMA (Code Division Multiple Access), significant …