Hybrid Digital/RF Envelope Predistortion Linearization for High Power Amplifiers in Wireless Communication Systems Wangmyong Woo 151 Pages Directed by Dr. J. Stevenson Kenney The objective of this research is to implement a hybrid digital/RF envelope predistortion linearization system for high-power amplifiers used in wireless communication systems. It is well known that RF PAs have AM/AM (amplitude modulation) and AM/PM (phase modulation) nonlinear characteristics. Moreover, the distortion components generated by a PA are not constant, but vary as a function of many input conditions such as amplitude, signal bandwidth, self-heating, aging, etc. Memory effects in response to past inputs cause a hysteresis in the nonlinear transfer characteristics of a PA. This hysteresis, in turn, creates uncertainty in predictive linearization techniques. To cope with these nonlinear characteristics, distortion variability, and uncertainty in linearization, an adaptive digital predistortion technique, a hybrid digital/RF envelope predistortion technique, an analog-based RF envelope predistortion technique, and a combinational digital/analog predistortion technique have been developed. A digital adaptation technique based on the error vector minimization of received PA output waveforms was developed. Also, an adaptive baseband-to-baseband test system for the characterization of RF PAs and for the validation of linearization algorithms was implemented in conjunction with the adaptation technique. To overcome disadvantages such as limited correction bandwidth and the need for a baseband input signal in digital predistortion, an adaptive, wideband RF envelope predistortion system was developed that incorporates a memoryless predistortion algorithm. This system is digitally controlled by a look-up table (LUT). Compared with conventional baseband digital approaches, this predistortion architecture has a correction bandwidth that is from 20 percent to 33 percent wider at the same clock speeds for third to fifth order IMDs and does not need a digital baseband input signal. For more accurate predistortion linearization for PAs with memory effects, an RF envelope predistortion system has been developed that uses a combination of analog-based envelope predistortion (APD) working in conjunction with digital LUT-based adaptive envelope predistortion (DPD). The resulting combination considerably decreases the computational complexity of the digital system and significantly improves linearity and efficiency at high power levels.

¡@¡@This paper is refer to the chapter 1 to chapter 5 (except chapter 4 ) of the book, Monte Carlo Statistical Methods(second edition), the author is Robert and Casella(2004). The goal is to translate the chapter 1 to chapter 5 contents of this book into Chinese, modify the mistakes, add the details of the examples, translate the algorithm of the examples into Mathematica(7th) codes, and use the Simulated Annealing method to deal with the estimation of parameters by rounding data, and discuss the results. This paper provides Mathematica(7th) codes of almost every example, and show the actual results, so it can be regarded as a toolbook for those people who are interested in reading this book or may solve some problems related to those examples.

This thesis improved the structure of traditional envelope elimination and restoration transmitter by replacing the analog components of envelope detector and limiter using digital processing technique of polar transformation. Envelope signal was modulated by delta-sigma modulation, which could suppress the quantization noise and would be good for integrated circuit design. The front end analog circuits of transmitter used high efficiency class-S and class-E power amplifiers to amplify envelope and phase signal separately and finally combined them at the output of class-E power amplifier. The RF transmitters using polar modulation had advantages of high efficiency and linearity when transmitting high PAPR-valued digital modulation signals. For example, when transmitting the QPSK-modulated signal with 900MHz carrier and 1Msps data rate, the transmitter was measured with efficiency as high as 60%, ACPR above 34dB, and EVM less than 6.5%.

The aim of this study was to investigate the thermal performance of residential units in the Middle East Technical University (METU) Campus, Ankara. The study was conducted on the unoccupied residential units to eliminate the occupant interventions. There were only three unoccupied residential units in the study period, hence sample was considered as randomly selected. Case study units were triplex row houses and all physical characteristics were identical apart from their orientations. The thermal performance of these three residential units was assessed by compiling data on temperature and relative humidity from a number of their rooms on certain days in January and February. The study was conducted in winter months, because heating loads are more significant than cooling loads for energy consumption in Ankara / the measurement period was determined according to the coldest days of the year. In this context, the temperature and humidity charts were evaluated and one of the units was simulated using the software tool Ecotect v.5.20. The simulation temperature charts demonstrate similar behavior and trends as the measured temperature / although, it was approximately 4 0C lower than the measured temperature. The possible reason for such a difference may be the precision of the material properties. Six different calibrations were tested by changing the thermal properties of the envelope materials to obtain comparable results with the measured temperature readings. Based on the calibrated model, it was found that an increase in the U-value of the envelope materials did not have a significant effect on the simulated temperature charts.

The amino-terminal 33 amino acids of the baculovirus integral membrane protein, ODV-E66, are sufficient for localization of fusion proteins to viralinduced intranuclear microvesicles (MV) and occlusion derived virus envelopes during infection, and has been termed the sorting motif (SM). When abundantly expressed, SM-fusions are also detected in the inner nuclear membrane (INM), outer nuclear membrane and endoplasmic reticulum of infected cells, suggesting proteins with the SM use the same trafficking pathway as cellular INM proteins to traffic to nuclear membranes. This study identifies the essential characteristics required for sorting of the SM to the INM of uninfected cells, and the MV and ODV envelopes of infected cells. These features are an 18 amino acid transmembrane sequence that lacks polar and charged amino acids (a.a.) with a cluster of charged a.a. spaced 5-11 residues from the end of the transmembrane sequence. A comparison of the a.a. sequence of these SM features with cellular INM proteins shows the features are conserved. The model of INM protein sorting and localization predicts the only known sorting event during INM protein trafficking is immobilization/retention in the INM. This study uses confocal microscopy and fluorescence recovery after photobleaching to compare the localization and mobility of lamin B receptor (LBR) fusions (which contain SM-like sequences) to a viral SM fusion when expressed in either mammalian or insect cells. The results show that immobilization is not necessarily required for accumulation of proteins in the INM. Furthermore, the results from infected cells show that an active sorting event, likely independent of immobilization, can distinguish the viral SM from cellular sequences similar to the SM. The results of this study show that sorting of proteins to the INM can be mediated by the viral SM or INM protein SM-like sequences that can function either independent of, or in addition to, immobilization. These data combined with recent reports suggest that in addition to diffusion:retention a signal mediated mechanism for sorting and localization to the INM can occur.

Die Familie der Retrovirinae wird in zwei Unterfamilien untergliedert, die Orthoretrovirinae und die Spumaretrovirinae. Foamyviren stellen aufgrund einiger besonderer Eigenschaften die einzigen Vertreter dieser Unterfamilie, die sie als Bindeglied zwischen den Retroviren und den Hepadnaviren erscheinen lassen. So erfolgt beispielsweise die reverse Transkription des viralen Genoms nicht erst nach Eintritt in die Zielzelle, sondern, anders als bei Orthoretroviren, bereits in der Produzentenzelle noch während oder kurz nach der Morphogenese. Diese Eigenschaft teilen Foamyviren mit den Hepadnaviren ebenso wie die obligate Koexpression der Kapsidproteine mit den viralen Hüllproteinen für die Freisetzung von Viruspartikeln. Im Gegensatz zu Orthoretroviren sind Foamyviren folglich nicht in der Lage virusähnliche Partikel (VLP) zu sekretieren und die spezifische Funktion des PFV Env Proteins kann nicht durch heterologe Hüllproteine übernommen werden. Die Synthese des PFV Env Vorläuferproteins erfolgt am rER, wobei es eine Typ III Membrantopologie erhält, mit sowohl dem N- als auch dem C-Terminus im Zytoplasma. Während des Transports des Proteins zum Ort der Partikelknospung, wird es posttranslational im Golgi-Apparat, oder dem trans-Golgi Netzwerk, durch Furin oder eine Furin-ähnliche Protease in drei partikelassoziierte Untereinheiten prozessiert. Eine Partikelassoziation retroviraler Signalpeptide ist bislang nur für Foamyviren nachgewiesen worden, genauso wie eine essentielle Rolle dieses Proteins bei der Interaktion zwischen dem

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 89-99).

The bacterial cell wall, composed of peptidoglycan (PG), is an essential component of the cell envelope. This macromolecular structure fortifies the cell membrane, determines cell shape, and helps prevent osmotic lysis. The synthesis and remodeling/recycling of this polymer is mediated by PG synthases and hydrolases, respectively. Proper control of the PG hydrolases is particularly important since misregulation of these enzymes can lead to lethal breaches in the cell wall. Surprisingly, however, the precise molecular mechanisms governing the activities of these enzymes remain poorly understood. To help understand how PG hydrolases are regulated, I examined how their activity is controlled during cytokinesis in Escherichia coli. One important class of PG hydrolases necessary for cell division is the LytC-type amidases (AmiA, AmiB and AmiC). These enzymes require activation by the LytM factors EnvC and NlpD. My work focused on elucidating the mechanism by which the LytM factors activate the amidases. Using a genetic enrichment strategy, I isolated amiB misregulation mutants. Interestingly, the mutations mapped to a region of AmiB found only in cell separation amidases. Structural analysis of an AmiB ortholog indicates that this region corresponds to an alpha-helical domain that appears to occlude the active site. Thus, activation of the amidases by the LytM factors likely occurs via a conformational change that displaces the regulatory helix from the active site. In addition to amidase regulation, I also investigated how the LytM activators are recruited to, and regulated at the site of division. Using genetic and biochemical approaches, I showed that EnvC is directly recruited to the division site by FtsEX, an ATP-binding transporter- like complex. Interestingly, ATPase-defective FtsEX derivatives can still recruit EnvC to the divisome, but fail to promote cytokinesis. These results support a model where conformational changes induced by the ATPase activity of FtsE are directly and specifically transmitted to the amidases via FtsX and EnvC. This model is attractive because it provides a mechanism for converting the potentially dangerous activity of septal PG splitting into a discrete process which can be cycled on and off in coordination with the division process.

Macrophages are target cells for human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infection that serve as viral reservoirs in brain, lung, gut, and other tissues, and play important roles in disease pathogenesis, particularly HIV/SIV-associated neurological disease. Macrophages express low levels of the HIV/SIV receptor CD4, but mechanisms by which macrophage-tropic viruses use low CD4 to mediate spreading infections are poorly understood. One mechanism involves enhanced envelope glycoprotein (Env) interaction with CD4 or CCR5, but this phenotype is frequently associated with increased neutralization sensitivity to antibodies targeting CD4/CCR5 binding sites. Moreover, this mechanism does not explain how these neutralization-sensitive viruses evade immune responses while establishing spreading infections. In this dissertation, we sought to identify SIV Env determinants for macrophage tropism and characterize mechanisms by which they enhance virus replication in macrophages. To identify viral variants capable of inducing macrophage-associated pathogenesis, we cloned Env sequences from SIV-infected macaques at early and late stage infection, and identified an early variant in blood that shares >98% sequence identity with the consensus sequence of late variants in brain from macaques with neurological disease. SIV clones encoding this Env variant mediated high levels of fusion, replicated efficiently in rhesus PBMC and macrophages, and induced multinucleated giant cell formation upon infection of macrophage cultures. We identified an N-linked glycosylation site, N173 in the V2 region, as a determinant of macrophage tropism. Loss of N173 enhanced SIVmac239 macrophage tropism, while restoration of N173 in SIVmac251 reduced macrophage tropism, but enhanced neutralization resistance to CD4/CCR5 binding site antibodies. SIVmac239 N173Q, which lacks the N173 glycosylation site, mediated CD4-independent fusion and cell-to-cell transmission with CCR5-expressing cells, but could not infect CD4-negative cells in single-round infections. Thus, CD4-independent phenotypes were detected only in the context of cell-cell contact. The N173Q mutation had no effect on SIVmac239 gp120 binding to CD4 in BIACORE and co-immunoprecipitation assays. These findings suggest that loss of the N173 glycosylation site increases SIVmac239 replication in macrophages by enhancing CD4-independent cell-to-cell transmission through CCR5-mediated fusion. This mechanism may facilitate escape of macrophage-tropic viruses from neutralizing antibodies, while promoting spreading infections by these viruses in vivo.

The HIV-1 envelope glycoprotein, Env, facilitates the translocation of the viral capsid across the cellular membrane. Env is a trimer of hetero-dimers composed of a gp120 subunit and gp41 transmembrane protein. The gp120 subunit binds the primary receptor, CD4, leading to conformational changes of Env that then promote binding to the coreceptor, principally CCR5 or CXCR4. As the sole protein on the surface of the virion, Env is under continuous pressure from the host's antibody response. Two classes of antibodies target the highly conserved receptor-binding sites of gp120: CD4-binding site (CD4bs) and CD4-induced (CD4i) antibodies.