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Energy usage has become an important issue in wireless communication systems. The energy-intensive nature of wireless communication has spurred concern over how best systems can make the most use of this non-renewable resource. Research in energy-efficient design of wireless communication systems show that one of its challenges is that the overall performance of the system depends, in a coupled way, on the different submodules of the system i.e. antenna, power amplifier, modulation, error control coding, and network architecture. Network architecture implementation strategies offer protocol software implementors an opportunity of incorporating low-power strategies into the design of the network protocols used for data communication. This dissertation proposes a methodology that would allow a software protocol implementor to analyze the power consumption of a wireless communication system. The foundation of this methodology lies in the understanding of the formal specification of the wireless interface network architecture which can be used to predict the performance of the system. By extending this hypothesis, a protocol implementor can use the formal specification to derive the power consumption behaviour of the wireless system during a normal operation (transmission or reception of data). A high-level formalism like state-transition graphs, can be used to track the protocol processing behaviour and to derive the associated continuous-time Markov chains. Because of their diversity, Markov reward models(MRM) are used to model the power consumption associated with the different states of a specified protocol layer. The models are solved analytically using the Mobius performance and dependability tool. Using the MRM accumulation and utilization measures, a profile of the power consumption is generated. Results from the experiments on the protocol layers show the individual power consumption and utilization of the different states as well as the accumulated power consumption of different protocol layers when compared. Ultimately, the results from the reward model solution can be used in the energy-efficient design of wireless communication systems. Lastly, in order to get an idea of how wireless communication device companies handle issues of power consumption, we consulted with the wireless module engineers at Siemens Communication South Africa and present our findings on current practices in energy efficient protocol implementation.

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The purpose of the study was to determine the efficacy of touch sensitive computer screens in focusing attention on a specific academic task. Forty nondelayed and forty delayed kindergarteners were compared as to their rates of task completion and performances on traditional computer keyboards versus touch sensitive screens. Two eight cell repeated measures experimental designs were used to compare the selective attention process of the nondelayed and delayed pupils. The two dependent variables manipulated in the study were two types of computer input device and the two developmental levels of the subjects. The dependent variable consisted of the number of previously unlearned French number words mastered through four performance measures involving speed, computer recall, noncomputer recall and noncomputer recognition.FINDINGSAs analyzed by a three factor MANOVA, a significant difference in the rate of task completion was shown in favor of the touch screens for all subjects in touching the sequential letters of the alphabet. Although there appeared to be no significant differences in noncomputer recall and recognition post tests, a four factor MANOVA verified significant differences in the subjects' computer recall post tests.CONCLUSIONSThe data supports the conclusion that the use of the touch sensitive screen facilitates the focus of attention (selective attention) on specific academic tasks and thus increases the rate of learning and degree of integration of new information. The degree of compatibility between the learner and the computer input device is greater with touch screens than with traditional keyboards for both nondelayed and delayed kindergarteners.The speed of completing the sequential touching of the alphabet letters was significantly faster for the touch screen than the traditional keyboard input. For mastery of information learned, the analyzed findings suggest a higher degree of recall for information learned through the touch screen intervention over the same instructional tasks with keyboard input.As the result of this key study, it is suggested future research investigations will expand the use of computers beyond educational drill, repetition, and games. Future investigations into the relationships between cognitive processing and the individualization of CAI could involve various age ranges, exceptionalities, and developmental comparisons. / Department of Special Education

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Graduation date: 1982

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