Browsing by Subject "Association"
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Item Association and spectrum sharing in cellular networks(2016-12) Gupta, Abhishek K.; Andrews, Jeffrey G.; Heath, Robert W., Ph. D.; Baccelli, Francois; Shakkottai, Sanjay; Vikalo, Haris; Visotsky, EugeneMany models have been proposed to evaluate performance of cellular communication systems. However, the emergence of new technologies have changed cellular systems significantly, and requires new modeling and analysis approaches. This dissertation studies network level optimization concerning cell association and spectrum sharing. As the first contribution, the dissertation presents a framework to investigate downlink multi-antenna heterogeneous networks with flexible cell selection and shows that a simple selection bias-based cell selection criterion closely approximates more complex selection rules to maximize mean the signal-to-interference-plus-noise- ratio (SINR). Under this simpler cell selection rule, the exact expressions for coverage probability and achievable rate of a typical user are derived along with an approximation of the coverage optimal cell selection bias. In the second contribution, the dissertation considers a cellular system where users are simultaneously connected to multiple base stations (BSs) to decrease blockage sensitivity and proposes a framework to analyze the correlation in blocking among multiple links. It evaluates the gains of macro-diversity in the presence of random blockages along with the impact of the blockage size. In the third contribution, the dissertation considers spectrum sharing among millimeter wave (mmWave) operators. A two-level architecture is proposed to model a mmWave multi-operator system and the SINR and per-user rate distribution are derived in the presence of spectrum and infrastructure sharing. It is shown that due to narrow beams, license sharing among operators improves system performance by increasing the per-user rate, even when there is no explicit coordination. In the fourth contribution, this analysis is extended to include static coordination among operators in the form of secondary licensing. A framework is developed to model a mmWave cellular system with a primary operator that has an ``exclusive-use'' license with a provision to sell a restricted secondary license to another operator that has a maximum allowable interference threshold. This licensing approach provides a way of differentiating the spectrum access for the different operators. Results show that compared to uncoordinated sharing, a reasonable gain can be achieved using the proposed secondary licensing, especially for edge rates.Item Differential Effects of Association and Semantics on Priming and Memory Judgments.(Texas Tech University, 2008-08) Buchanan, Erin M.; Maki, William S.; Taraban, Roman M.; DeLucia, Patricia R.; Maki, Ruth H.Semantic memory is the storage of world knowledge or facts, while associative memory contains information about how words are related in context of speech or writing (Tulving, 1993; Nelson, McEvoy, & Dennis, 2000). For example, the word pair CAT-DOG is semantically related because cats and dogs have many of the same features, such as legs, tails, fur, house pets, etc. CAT-DOG is also associatively related because the words appear together frequently in text such as “it’s raining cats and dogs”. Research examined to see if these two types of memory are separable or if all context and dictionary knowledge are contained in one memory system (Lucas, 2000). Currently, results are mixed on the separability of these two memory systems, where effects are seemingly dependent on stimuli used. Previous studies had difficulty controlling for both relationships for word pairs, meaning that word pairs were dually related despite claims for single relationships. Several studies were designed using large semantic and associative word norm databases (Maki, McKinley, & Thompson, 2004; Nelson, McEvoy, Schreiber, 2004). These databases made it possible to create separate word lists; so only one relationship (semantic or associative) was present. From there, priming for both memory types was tested using a rapid serial visual presentation task (RSVP) and judgment task. In the RSVP task, participants watched a very fast presentation of symbols, which were either distractors or target words. Participants were required to name the target word they saw among the distractors. Priming occurred when target words that were related were named more than unrelated target words. In a judgment task, participants were asked to read two words and rate how much they thought the words belonged together based on their feature overlap (how many features they share) or their associative relationship (how many people out of 100 would put them together). Judgments were part of the related word pair for the RSVP task to create priming. Priming for both relationships was found, which indicated that these two systems were separate. Judgments showed that people could separate the two memory systems when making judgments. Associative judgments were processed by associative information but not semantics, while semantic judgments required both associative and semantic information. However, attentional differences in judgments found previously did not transfer to priming results (Buchanan, Maki, & Patton, 2007). These studies, including priming tasks, showed that information appeared to be readily accessible (including semantic information) but in a different order of processing. Associative information appears to be processed earlier at a word or lexical level while semantic information is processed later and in a separate store. From there, judgment processes might occur even later than information processing used for priming.Item The impact of light rail transit on residential rental market : case study of Dallas Area Rapid Transit(2016-08) Haque, Antora Mohsena; Zhang, Ming, 1963 April 22-; Wegmann, JakeThis research was undertaken to quantify the relationship between residential rent and proximity to light rail transit in Dallas, an auto-oriented city. This correlation is of importance to real estate developers and transportation planners as they seek to make the most efficient use of developable land and to decide on the allocation of funding for future transportation projects. This study shows that proximity to DART rail stations is associated with residential rent up to half mile radius area of the stations. Hedonic regression models in simple Ordinary Least Squares (OLS) and semi log form were used for the analysis. The semi log model showed that light rail stations have the strongest relationship with rent in the 0.1 mile to 0.2 mile distance buffer, where the rent/sq. ft. is 20.92% higher than for units between 0.4 and 0.5 miles distance from stations. After 0.2 miles distance from the stations, the rent starts to drop and continues to go down till 0.5 miles distance from a station. The simple OLS model showed similar results and according to this model within 0.1 to 0.2 mile buffer area the rent is 27.6 cents/sq. ft. higher than the rent/sq. ft. in the 0.4 to 0.5 mile buffer area. This result will help to manage the extent of investment in light rail in Dallas in the future.