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Multicasting in Long-Term Evolution (LTE) environments poses several challenges if it is to be reliably implemented. Neither retransmission schemes nor Forward Error Correction (FEC), the traditional error correction approaches, can be readily applied to this system of communication if bandwidth and resources are to be used efficiently. A large number of network parameters and topology variables can influence the cost of telecommunication in such a system. These need to be considered when selecting an appropriate error correction technique for a certain LTE multicast deployment. This dissertation develops a cost model to investigate the costs associated with over-the-air LTE multicasting when different error correction techniques are applied. The benefit of this simplified model is an easily implementable and fast method to evaluate the communications costs of different LTE multicast deployments with the application of error correction techniques. / MIng (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2014

In epidemiological studies of an exposure-response association, often only a mismeasured exposure is taken on each individual of the population under study. If ignored, exposure measurement error can bias the estimated exposure-response association in question. A reliability study may be carried out to estimate the relation between the mismeasured and true exposure, which could then be used to adjust for measurement error in the attenuated exposure-response relationship. However, taking repeated exposure measurements may be expensive. Given a fixed total study cost, a two-stage design may be a more efficient approach for regression parameter estimation compared to the traditional single-stage design since, in the second-stage, repeated measurement is restricted to a sample of first-stage subjects. Sampling the extremes of the first-stage exposure distribution has been shown to be more efficient than random sampling.

This thesis explores the impact of peer feedback on two secondary level classrooms studying English as a foreign language in Taiwan. The effectiveness of teacher-led feedback has consistently been the focus of the relevant literature but relatively fewer studies have experimentally investigated the impact of peer-led feedback on learning. This research is based on the belief that the investigation of the process of peer-led feedback, as well as the effectiveness of peer-led correction, will enhance our understanding of learners’ communicative interactions. These data will allow us the opportunity to provide suggestions for successful second/foreign language learning. This study was conducted following a mixed-methods quasi-experimental design involving a variety of data collection and analysis techniques. Observations of peer-peer dialogues taken from a Year 7 and a Year 8 class were analysed using content analysis, in order to classify the types of peer feedback provided by the Year 7 and Year 8 learners. Pre-and post-measures, including English speaking tests, questionnaires, and checklists, were examined with non-parametric statistical tests used to explore any changes in relation to the learners’ speaking development after the quasi-experiment. Key findings included frequency and distribution of seven types of peer feedback, as used by the Year 7 and Year 8 learners, and the statistical results that revealed the differences between the pre-and post-measures. Among the seven types of peer feedback (translation, confirmation, completion, explicit indication, explicit correction, explanation and recasts), explicit correction and translation were the two techniques used most frequently by the learners. Post-test results indicated an improvement in the learners’ speaking performance. The results of pre- and post-questionnaires and pre- and post-checklists showed different levels of change in the learners’ self-evaluation of their own ability to speak English, as well as their attitudes towards corrective feedback. These results allow us to gain insight into the nature of peer interaction in communicative speaking activities as well as learners’ motives behind their feedback behaviours. Additionally, the results shed light on learners’ opinions towards corrective feedback that they received or provided in peer interaction. Further, the results yield a deepened understanding of impacts of peer feedback on L2 development by examining changes in learners’ speaking performance, self-confidence in speaking English and self-evaluation of their own ability to speak English after a peer-led correction treatment. In conclusion, the study suggests that adolescent learners are willing and able to provide each other with feedback in peer interaction. The feedback that they delivered successfully helps their peers to attend to form and has positive impacts on their peers’ English- speaking performance. Moreover, the study provides explanations for learners’ preference for certain types of feedback techniques, which hopefully helps to tackle the mismatch between teachers’ intentions and learners’ expectations of corrective feedback in the L2 classrooms.

International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, California / The bit rates of telemetry systems are increasing rapidly. Higher bit rates occupy more spectra and result in decreased link margin. The major signal parameters that affect the spectral occupancy and bit error probability (BEP) of binary pulse code modulation (PCM)/frequency modulation (FM) signals are the bit rate, code, premodulation filter, and peak deviation. The measured spectral occupancy is also affected by the spectrum analyzer (or other measurement equipment) settings. Additional parameters that affect the BEP include the receiver intermediate frequency (IF) filter, the FM demodulator, and the bit detector. This paper will present the effects of these parameters on the measured 99% and -60 dBc bandwidths and the BEP of binary PCM/FM telemetry signals. Normalized BEP and bandwidth curves will be presented.

International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This paper describes algorithms implemented by the Magellan High Rate Processor to recover radar data corrupted by the failure of an onboard tape recorder that dropped bits. For data with error correction coding, an algorithm was developed that decodes data in the presence of bit errors and missing bits. For the SAR data, the algorithm takes advantage of properties in SAR data to locate corrupted bits and reduce there effects on downstream processing. The algorithms rely on communication approaches, including an efficient tree search and the Viterbi algorithm to maintain the required throughput rate.

Master of Science / Department of Agricultural Economics / Glynn T. Tonsor / The past several years has marked one of the most heightened periods of fed cattle basis volatility since the installment of live cattle futures contracts. Understanding basis, the difference between local cash price and the futures contract price, is imperative when making marketing and procurement decisions. In the face of increased volatility, the ability to produce accurate basis expectations is no simple task. The purpose of these analyses was to develop econometric models to determine the greatest influencers of fed cattle basis, to test the presence of structural changes in the determinants of fed cattle basis, and to compare out-of-sample forecasting performance. This study analyzed in-sample econometric models using monthly data from January 2003 through September 2016, then compared the results of the competing models. Using the same time period, we then identified the presence of structural breaks in the data. Furthermore, this study analyzed the out-of-sample forecasting performance for January 2012 through September 2016. The out-of-sample results were then compared to in-sample estimations and historical average basis models. The in-sample estimations indicated the important factors that influence fed cattle basis. The results indicate that there are multiple structural breaks present in the determinants of fed cattle basis examined during this study. We can robustly conclude that there was a market structural break present in the fourth quarter of 2013 and within the 2005-2006 time period. The results indicate that the out-of-sample regression estimations were outperformed by historical average models and did not improve our ability to accurately forecast basis. Overall, a 3 or 4 year historical average model should be preferred over econometric estimations when forecasting fed cattle basis.

Master of Science / Statistics / Weixing Song / In this report, an improved estimation procedure for the regression parameter in simple linear regression models with the Laplace measurement error is proposed. The estimation procedure is made feasible by a Tweedie type equality established for E(X|Z), where Z = X + U, X and U are independent, and U follows a Laplace distribution. When the density function of X is unknown, a kernel estimator for E(X|Z) is constructed in the estimation procedure. A leave-one-out cross validation bandwidth selection method is designed. The finite sample performance of the proposed estimation procedure is evaluated by simulation studies. Comparison study is also conducted to show the superiority of the proposed estimation procedure over some existing estimation methods.

D.Phil. / none / Prof. W.F. Harris