Selected mapping (SLM) is a well-known technique used to reduce the peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. Although SLM scheme can reduce PAPR efficiently, the side information (SI) must be transmitted to the receiver to indicate the candidate signal that generates the OFDM signal with the lowest PAPR. Robust channel coding schemes are typically adopted to prevent erroneous decoding of SI, leading to the lower bandwidth efficiency. To reduce PAPR efficiently and avoid the bandwidth efficiency loss caused by the transmission of SI, two novel PAPR reduction methods are proposed in SFBC MIMO-OFDM systems with two transmitter antennas that employs the Alamouti coding. The candidate signals are constructed in the frequency-domain and time-domain in the first proposed scheme and the second proposed scheme, respectively. In addition, the orthogonality of the space frequency block code is preserved resulting in the data recovery and the corresponding SI can be easily obtained from the conventional Alamouti detection method for both transmission methods. Simulation results show that the BER performance of a SFBC MIMO-OFDM system with the proposed SI detection algorithm is very close to that of perfect SI detection if the extension factor is larger than 1.3.

In multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system which was used space frequency block coding (SFBC) method. It order to reduce the peak-to-average power ratio in several transmit antennas. We proposed two new architectures to simply the computational complexity on transmitter. According to the characteristics of SFBC structure which have M transmitter antennas. We can decomposed the interleaving subcarrier groups by used conversion vector to circular convolution with signal vector and shrink the inverse fast Fourier transform (IFFT) points. Therefore it can do the SFBC coding operation in time domain. By using combination of different cyclic shifts and phase rotations in U subcarrier groups can generate the P candidate signals. And it wouldn¡¦t increase the number of IFFT. The proposed transmitter architectures can improve the major drawback of high computational complexity in traditional selected mapping (SLM). The traditional SLM generate the P candidate signals needs MP IFFT units. Then in the condition of lose a little PAPR reduction performance, we can save the most of computational complexity.

The efficacy of aural modeling in music education at the primary and secondary levels is well documented, and anecdotal evidence among university studio voice teachers abounds. However, this topic has not previously been explored with undergraduate level singers using acoustic analysis of the singing voice. This investigation utilized a survey on listening behaviors to examine undergraduate voice students’ use of recorded aural models. In addition, an empirical study measured the effect of repeated exposure to recorded aural models on participants’ vocal production. Research was conducted at Southwestern University, a private liberal arts institution in Georgetown, Texas. Study participants were divided into two groups. The control group performed a newly-composed melody after a recorded aural model of the melody was played a single time. The experimental group completed 10-minute listening assignments once a day for a five-day period before performing the same melody. Data between the non-listening and listening groups was compared. Using a second newly composed melody, the control group then completed a five-day listening assignment and performed the second melody. Pre- and post-listening data from this group of subjects was compared. Listening assignments were adapted from a speech pathology remediation technique known as auditory bombardment. They involved listening to multiple repetitions of the recorded aural model without attempting to practice singing the melody. The study measured four acoustic parameters: musical accuracy (pitch and rhythm), vowel/consonant articulation, use of vibrato, and ratio of power between overtones above and below 2 kHz. The listening behavior survey revealed that most students use recorded aural models in their practice time. However, results indicated that students would benefit from professional quality aural models and specific information about appropriate time parameters for listening activities. Results of the empirical study revealed a statistically significant 20-30% improvement in vocal production in both the experimental listening group and the control group post-listening. These data demonstrate that focused periods of listening to an aural model are effective in improving vocal production, even within a short period of time. The results of this study support the inclusion of aural modeling in the applied voice studio. / text

Selecting a suitable power source, during the design process, for a stand-alone soya business unit is challenging and complex. Especially with the aim of optimizing electrical and thermal energy, as well as minimizing the life cycle cost. During the design and development of a soya business unit it was realized that a design tool is needed to assist with the decision making process when selecting a power source. Waste heat can be recovered from either or both the exhaust gas and cooling system of the power source and can be utilized in the soya process. Research of available literature revealed no design tool to assist with the decision making process of the stand-alone business unit and consequently lead to this study. This dissertation presents different possible power sources that could be utilized in supplying energy to the business unit, as well as design tools available. Advantages and disadvantages of the different power sources are discussed. The shortfalls of a number of the available design tools are also discussed. A diesel generator set was selected as the preferred power source for the business unit. Criteria for this selection included the price per kWhe generated, the ease of maintenance, the availability of the diesel generators in rural areas and the availability of diesel as a fuel. The diesel engine was characterized through experimental work for a more in depth understanding of the energy profile of the engine at part load conditions. These results were used as guidelines in the development of the design tool. The design tool was developed with the aim of being user friendly and versatile. The time intervals of the required load of the business unit are flexible. Different types of power sources and fuels can be used within the design tool. User defined heat exchangers are utilized to calculate the possible heat recovery from the power source. The design tool matches the available energy of different power sources at part load conditions with the required load profile of the soya business unit. It then eliminates power sources that would not be able to deliver the minimum required energy. The running cost is calculated for each of the remaining power sources and the power source with the minimum annualized cost, which includes capital cost, maintenance cost and fuel cost, is suggested. The design tool was verified against a base load condition of the soya business unit and the suggested power source showed a saving of 31,4% in electrical energy, an increased overall efficiency of 24,9% and a saving in annualized cost of 27,3%. The design tool can be used to optimize specific components and design options within a combined heat and power system. Sensitivity analysis can be performed with the design tool to determine various influences on the designed system. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2008.

Selecting a suitable power source, during the design process, for a stand-alone soya business unit is challenging and complex. Especially with the aim of optimizing electrical and thermal energy, as well as minimizing the life cycle cost. During the design and development of a soya business unit it was realized that a design tool is needed to assist with the decision making process when selecting a power source. Waste heat can be recovered from either or both the exhaust gas and cooling system of the power source and can be utilized in the soya process. Research of available literature revealed no design tool to assist with the decision making process of the stand-alone business unit and consequently lead to this study. This dissertation presents different possible power sources that could be utilized in supplying energy to the business unit, as well as design tools available. Advantages and disadvantages of the different power sources are discussed. The shortfalls of a number of the available design tools are also discussed. A diesel generator set was selected as the preferred power source for the business unit. Criteria for this selection included the price per kWhe generated, the ease of maintenance, the availability of the diesel generators in rural areas and the availability of diesel as a fuel. The diesel engine was characterized through experimental work for a more in depth understanding of the energy profile of the engine at part load conditions. These results were used as guidelines in the development of the design tool. The design tool was developed with the aim of being user friendly and versatile. The time intervals of the required load of the business unit are flexible. Different types of power sources and fuels can be used within the design tool. User defined heat exchangers are utilized to calculate the possible heat recovery from the power source. The design tool matches the available energy of different power sources at part load conditions with the required load profile of the soya business unit. It then eliminates power sources that would not be able to deliver the minimum required energy. The running cost is calculated for each of the remaining power sources and the power source with the minimum annualized cost, which includes capital cost, maintenance cost and fuel cost, is suggested. The design tool was verified against a base load condition of the soya business unit and the suggested power source showed a saving of 31,4% in electrical energy, an increased overall efficiency of 24,9% and a saving in annualized cost of 27,3%. The design tool can be used to optimize specific components and design options within a combined heat and power system. Sensitivity analysis can be performed with the design tool to determine various influences on the designed system. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2008.

Orthogonal Frequency Division Multiplexing (OFDM) and Single Carrier Block Transmissions (SCBT) are located at the two opposite edges of block transmission concept. In this thesis a system which lies between OFDM and SCBT is proposed. The new system, namely Block Transmissions on Orthogonal Carriers (BTOC), can be considered as a hybrid form of OFDM and SCBT. BTOC system is investigated under the redundant filterbank precoders and equalizers framework. Peak to average power ratio (PAPR) of BTOC is formulated and compared with the PAPRs of OFDM and SCBT. Effect of frequency offset for BTOC is investigated and comparison between OFDM, SCBT, and BTOC is presented. Simulation results of Zero Padded OFDM (ZP-OFDM), SCBT, and BTOC are included.

Distortion-based crest factor reduction (CFR) algorithms were studied in orthogonal frequency division multiplexing (OFDM) and multiple-input multiple-output (MIMO) OFDM systems to reduce the nonlinear distortion and improve the power efficiency of the transmitter front-end. First, definitions of peak-to-average-power ratio (PAR) were clarified based on the power efficiency improvement consideration in the MIMO-OFDM systems. Next, error vector magnitude (EVM) was used as the in-band performance-evaluating metric. Statistical analysis of EVM was performed to provide concrete thresholds for the amount of allowable distortions from each source to meet EVM requirements in the standard. Furthermore, an effective CFR technique, constrained clipping, was proposed to drastically reduce the PAR while satisfying any given in-band EVM and out-of-band spectral mask constraints. Constrained clipping has low computational complexity and can be easily extended to the multiple-user OFDM environment. Finally, signal-to-noise-and-distortion ratio (SNDR) analysis for transceiver nonlinearities in the additive white Gaussian noise channel was investigated. An analytical solution was presented for maximizing the transceiver SNDR for any given set of nonlinear transmitter polynomial coefficients. Additionally, mutually inverse pair of transceiver nonlinearities was shown to be SNDR-optimal only in the noise-free case.

The purpose of this project was to explore the performance of methods for estimating stopping power ratio (SPR) from Hounsfield units (HU) using dual energy CT scans, rather than the standard single energy CT scans, with the aim of finding a method which could outperform the current single energy stoichiometric method. Such a method could reduce the margin currently added to the target volume during treatment which is defined as 3.5 % of the range to the target volume + 1 mm . Three such methods, by Taasti, Zhu, and, Lalonde and Bouchard, were chosen and implemented in MATLAB. A phantom containing 10 tissue-like inserts was scanned and used as a basis for the SPR estimation. To investigate the variation of the SPR from day-to-day the phantom was scanned once a day for 12 days. The resulting SPR of all methods, including the stoichiometric method, were compared with theoretical SPR values which were calculated using known elemental weight fractions of the inserts and mean excitation energies from the National Institute of Standards and Technology (NIST). It was found that the best performing method was the Taasti method which had, at best, an average percentage difference from the theoretical values of only 2.5 %. The Zhu method had, at best, 4.8 % and Lalonde-Bouchard 15.6% including bone tissue or 6.3 % excluding bone. The best average percentage difference of the stoichiometric method was 3.1 %. As the Taasti method was the best performing method and shows much promise, future work should focus on further improving its performance by testing more scanning protocols and kernels to find the ones yielding the best performance. This should then be supplemented with testing different pairs of energies for the dual energy scans. The fact that the Zhu and Lalonde-Bouchard method performed poorly could indicate problems with the implementation of those methods in this project. Investigating and solving those problems is also an important goal for future projects. Lastly the Lalonde-Bouchard method should be tested with more than two energy spectra.

Employing an error control code is one of the techniques to reduce the Peak-to-Average Power Ratio (PAPR) in an Orthogonal Frequency Division Multiplexing system; a well known class of such codes being the cosets of Reed-Muller codes. In this thesis, classes of such coset-codes of arbitrary linear codes are considered. It has been proved that the size of such a code can be doubled with marginal/no increase in the PAPR. Conditions for employing this method iteratively have been enunciated. In fact this method has enabled to get the optimal coset-codes. The PAPR of the coset-codes of the extended codes is obtained from the PAPR of the corresponding coset-codes of the parent code. Utility of a special type of lengthening is established in PAPR studies

Cette thèse a été effectuée dans le cadre du projet européen FP7 EMPHATIC (Enhanced Multicarrier Techniques for Professional Ad-Hoc and Cell-Based Communications). Plusieurs universités européennes et deux partenaires industriels: THALES Communications Security et CASSIDIAN ont participé à ce projet. L'objectif de ce projet est de développer, d'évaluer et de démontrer les apports des techniques multi-porteuses avancées, permettant une meilleure utilisation des bandes de fréquences radio existantes en fournissant des services de données à large bande, en coexistence avec les services traditionnels à bande étroite. Le projet porte sur l'application de radiocommunications mobiles professionnelles (Professional Mobile Radio : PMR). L'idée principale de ce projet est d'analyser la viabilité des systèmes à large bande utilisant des bancs de filtres (Filter Bank Multi Carrier : FBMC) conjointement avec une modulation d'amplitude en quadrature avec décalage (Offset Quadrature Amplitude Modulation : OQAM) dans le cadre de la 5ème génération (5G) des systèmes radio-mobiles. La modulation FBMC-OQAM se positionne comme candidate potentielle pour les futurs systèmes de communication. Cette modulation avancée offre de nombreux avantages tels que l’excellente localisation fréquentielle de sa densité spectrale de puissance (DSP), une robustesse au bruit de phase, aux décalages de fréquence ainsi qu’à l’asynchronisme entre les utilisateurs. Ces atouts, la rendent plus attrayant qu’OFDM pour l’application PMR, la radio cognitive (CR) et la 5G. Cependant, comme toute autre technique de modulation muti-porteuses, FBMC-OQAM souffre d’un facteur de crête ou d’un PAPR (pour Peak to Average Power Ratio) élevé. Lorsque l'amplificateur de puissance (AP), utilisé au niveau de l’émetteur, est opéré proche de sa zone non-linéaire (NL), ce qui est le cas dans la pratique, la bonne localisation fréquentielle de la DSP du système FBMC/OQAM est sérieusement compromise, en raison des remontées spectrales. Le premier objectif de cette thèse est de prédire l'étendue des remontées spectrales dans les systèmes FBMC-OQAM, introduites par la non-linéarité AP. Le deuxième objectif de ce travail est de proposer des techniques, pour les systèmes FBMC-OQAM, permettant la réduction du PAPR et la linéarisation de l’AP, afin d'atténuer les effets NL. L’utilisation des cumulants, a permis de prédire les remontées spectrales pour les signaux FBMC-OQAM après amplification NL. En outre, certains algorithmes de réduction du PAPR, basées sur des approches probabilistes et des techniques d'ajout de signaux, ont été proposés. La capacité de coexistence du système à large bande utilisant FBMC-OQAM avec des systèmes PMR à bande étroite en présence de PA a été analysée et il a été démontré que la coexistence est possible, à condition qu'il y est une bonne combinaison entre le recul du signal à l’entrée de l’AP (Input Back-Off : IBO), la réduction du PAPR et la linéarisation de l’AP. Enfin, une nouvelle technique de linéarisation de l’AP a été proposée pour le système FBMC-OQAM. / This thesis is part of the European FP7 EMPHATIC project (Enhanced Multicarrier Techniques for Professional Ad-Hoc and Cell-Based Communications) including various European universities and two main industrial partners: THALES Communications Security and CASSIDIAN. The EMPHATIC objective is to develop, evaluate and demonstrate the capability of enhanced multi-carrier techniques to make better use of the existing radio frequency bands in providing broadband data services in coexistence with narrowband legacy services. The project addresses the Professional Mobile Radio (PMR) application. The main idea is to analyze the viability of broadband systems based on filter-bank multi-carrier (FBMC) clubbed with o ffset quadrature amplitude modulation (OQAM) in the context of the future 5th Generation (5G) radio access technology (RAT). Increasingly, the FBMC-OQAM systems are gaining appeal in the probe for advanced multi-carrier modulation (MCM) waveforms for future communication systems. This advanced modulation scheme o ers numerous advantages such as excellent frequency localization in its power spectral density (PSD), a robustness to phase noise, frequency off sets and also to the multi-user asynchronism; making it more appealing than OFDM for PMR, cognitive radio (CR) and 5G RAT. However, like any other MCM technique, FBMC-OQAM suff ers from high PAPR. When the power amplifi er (PA) non-linearity, which is realistic radio-frequency impairment, is taken into account; the good frequency localization property is severely compromised, due to the spectral regrowth. The first objective of this PhD thesis is, to predict the extent of the spectral regrowth in FBMC-OQAM systems, due to the PA non-linearity. The second objective is to probe techniques for FBMC-OQAM systems, such as PAPR reduction and PA linearization, in order to mitigate the NL eff ects of PA. By cumulant analysis, spectral regrowth prediction has been done for FBMC-OQAM systems. Also, some algorithms for PAPR reduction, which are based on probabilistic approach and adding signal methods, have been proposed. The coexistence capability of the FBMC-OQAM based broadband system with the narrowband PMR systems in the presence of PA has been analyzed and it has been found that coexistence is possible, provided there is a symbiotic combination of PA Input Back-off (IBO), PAPR reduction and PA linearization. Finally, a novel PA linearization technique has been proposed for FBMC-OQAM.