Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Development of a cognitive array system(Montana State University - Bozeman, College of Engineering, 2010) Weber, Raymond Joseph; Chairperson, Graduate Committee: Richard Wolff; Yikun Huang (co-chair)This thesis proposes a design for a cognitive array system for next generation wireless communication systems, combining the techniques of cognitive radios and adaptive array systems. This novel array system allows for the possibility of greater spectral usage and reuse, and improved communication ranges. In this thesis, numerous algorithms were studied to map an RF environment in both spatial and spectral domains that would be useful in this system. Towards this goal, direction of arrival estimation, frequency sensing and spectral hole finding algorithms were studied, in addition to a joint frequency and direction of arrival estimation algorithm. Beamforming was also studied as a means of improving signal quality and increasing range. Once the direction to a target was found, localization and tracking were studied to further refine the target's position and change in position over time. After the algorithms were studied in simulation to determine their properties, hardware calibration was performed followed by laboratory tests of the methods with a uniform circular array testbed at Montana State University to verify the expected performances.Item Design and evaluation of test bed software for a smart antenna system supporting wireless communication in rural area(Montana State University - Bozeman, College of Engineering, 2008) Panique, Michael David; Chairperson, Graduate Committee: Richard Wolff; Yikun Huang (co-chair)This paper explores the design and development of a test bed to analyze feasibility of utilizing adaptive smart antennas in conjunction with high bandwidth WiMAX radio systems to achieve improved performance for mobile nodes and to suppress potential interference from unwanted signals. Although the new WiMAX standard offers the potential for using smart, adaptive antennas, this functionality has not been implemented. This design serves as a common platform for testing adaptive array algorithms including direction of arrival (DOA) estimation, beamforming, and adaptive tracking, as well as complete wireless communication with a WiMAX radio. Heavy emphasis will be placed on ease of implementation in a multi-channel / multi-user environment. Detailed here, is the design and development of an 8-channel adaptive smart antenna test bed for WiMAX radio systems. The test bed consists of an 8-element circular antenna array, a PC running a software interface, and RF receiver and transmission boards which enable DOA estimation and beamforming to take place. We have developed a LabVIEW interface for a PC controlled smart antenna test bed supporting two mobile targets. The main system has three components, DOA estimation and signal validation, beamforming (null steering or multi-beam), and target tracking. The interface is implemented in a modular fashion so that a maximum amount of flexibility is available to test bed users. The test bed was used in conjunction with MATLAB simulations to analyze DOA estimation, beamforming, and nullsteering algorithms necessary to realize a smart antenna system capable of handling multiple users and suppressing nearby strong interference. The results of tests run using the test bed showed that communication delay and hardware limitations on the RF transmission board were a limiting factor in the performance of the smart antenna system.Item Improved control system for process, voltage, and temperature compensation of CMOS active inductors(Montana State University - Bozeman, College of Engineering, 2011) Hollender, Reinhold Frederick William, III; Chairperson, Graduate Committee: James P. BeckerWireless communications play an increasingly large role in today's society. Today, many wireless functions are necessarily integrated into chips and other small packages to support miniaturized wireless devices such as cell phones, laptops, netbooks, etc. These Radio Frequency Integrated Circuits (RFICs) often require inductances to perform their function. Most RFICs utilize spiral inductors. Spiral inductors have their properties defined by their physical dimensions, often taking up large areas of IC real estate. There has been research into replacing these spiral inductors with active elements to reduce their size. However, these active inductors are based on parasitic elements that can vary significantly over temperature, supply voltage, and processing variations of the wafers themselves. This professional paper documents an improved control scheme to maintain correct active inductor behavior over process, voltage, and temperature variations in applications where the active inductor is used in a Wilkinson power divider.Item Wireless communication for sparse and rural areas(Montana State University - Bozeman, College of Engineering, 2007) Zhang, Mingliu; Chairperson, Graduate Committee: Richard WolffWireless technology experienced a fast development in the past few decades. However, research and investment in wireless communication so far has been focused mainly on high-density domains or fully connected networks. The technologies/solutions developed for above domains do not readily apply to rural and sparse domains. The users in rural and sparse areas are still served predominantly by either low-speed dialup access or have no data service available at all. This research work explores the largely overlooked rural and sparse domains, where distance, rough terrain and low node density are the key parameters driving system design and performance, from the perspectives of fixed wireless applications to mobile wireless applications. For fixed wireless applications, a baseline wireless network structure for rural and sparse areas is defined and the potential for improved high-speed fixed communication services in rural and remote areas is examined. The potential of using multi-hop network topologies in very sparse areas is explored. The cost benefits of several other emerging technologies and approaches are also investigated with the objective of finding cost-effective and affordable high-speed broadband communications solutions for rural and remote areas.