This dissertation presents a study of linearization techniques that have been applied to power amplifiers in the cellular communication industry. The objective of this work is to understand the limitations of power amplifiers, specifically the limitations introduced by the use of spectrally efficient modulation schemes. The digitization of communication systems has favored the use of new techniques and technologies capable of increasing the efficiency of costly power amplifiers. The work explores traditional and digital linearization systems; an algorithm based on the principles of natural recombination is proposed to directly address the limitations of previous embodiments. Previous techniques, although effective, have significant implementation costs that increase exponentially with the increasing signal bandwidths. The proposed software-hardware architecture significantly reduces implementation costs and the overall complexity of the design without sacrificing performance. To fulfill the requirements of this study, multiple systems are implemented through simulation and closed-loop hardware. Both simulation and hardware embodiments meet the expected performance metrics, providing validation of the proposed algorithm. The application of the algorithm to memory power amplifier linearization is a new approach to adaptive digital pre-distortion using narrowband feedback. The work will show performance improvements on an amplifier with memory effects suggesting that this technique can be employed as a lower-cost solution to meet requirements when compared to typical system implementations.

Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 189-194). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 189-194). Also available on the Internet.

Dissertation submitted in compliance with the requirements for the Masters Degree in Technology: Business Administration, 2008. / The aim of the study was to identify causes of churning, to find ways of managing it and to diagnose customers‟ communication needs. Furthermore the research tested the impact of messaging services on customer retention and whether these services could compensate for the declining revenue or become new cash cows for service providers. The units of analyses were young people of ages ranging from 15 to 24. This group was chosen because it was found, during the study, that they used new services more often than any other age group. The initial plan, however, was to interview the entire population of cellphone users. Stratified random sampling was used to randomly select the units of analysis. Interviews were conducted at the homes of respondents, in the streets and at a shopping centre. Causes of customer churning were found to be billing by service providers that confused customers and „better phone deals offered by the competitors‟ resulting in some of the respondents switching providers. Other aspects about which respondents complained and which therefore could cause churning are „poor network quality‟, „confusing pricing structure‟ and „long waiting on customer care line‟. The respondents indicated that their communication needs could be satisfied by services that are easy to use, a helpful customer care agent and being able to retain a number when switching a service provider. Therefore churning could be managed by removing or reducing the causes of it and attracting the customers by meeting their communications needs, which are, improving customer care service and designing services that are easy to use. The research was inconclusive on the messaging services. Of the three new messaging services that were studied, only one was extremely popular, while the other two were hardly used. Instant messaging was the second most used service to voice and SMS and it was also ranked second, in order of importance. The other two messaging services, mobile email and MMS, received low rankings from the respondents. In addition more than a quarter (27%) of the respondents had never used mobile email. The implications of these findings are that service providers should improve their customer care service and design services that are easy to use.

Diss. ETH No. 14577. Eidgenöss. Techn. Hochsch., Diss.--Zürich, 2002.

Thesis (M.App.Sc.) - Carleton University, 2003. / Includes bibliographical references. Also available in electronic format on the Internet.

Thesis (M. App. Sc.)--Carleton University, 2004. / Includes bibliographical references (p. 82-83). Also available in electronic format on the Internet.

Thesis (MCIS - Computer and Information Sciences) -- AUT University, 2007. / Includes bibliographical references. Also held in print (xii, 100 leaves : ill. ; 30 cm.) in the Archive at the City Campus (T 384.5 COS)

Thesis (Ph.D.)--University of Western Australia, 2008.

Thesis (M. Eng.)--Carleton University. 1993. / Also available in electronic format on the Internet.