Beamspace ESPRIT for multidimensional arrays and synchronization aspects of PSAM
Abstract
This thesis covers two topics of great interest in communications and signal processing: direction finding using antenna arrays and synchronization aspects of pilot symbol assisted modulation. First, the direction of arrival estimation problem is explored for plane waves propagating across an antenna array. Joint azimuth and elevation angle estimation requires a two dimensional array; however, these arrays have a large number of sensors which increases the complexity of any algorithm. To compensate, multidimensional multirate techniques are employed to combine two existing reduced complexity methods, beamspace processing and ESPRIT. A modified ESPRIT algorithm is then developed which obtains the two source directions from an eigenvalue-eigenvector pair. Second, synchronization aspects of wireless communications are explored. Pilot symbol assisted modulation is a method to reduce the effects of fading in mobile communications by periodically inserting known symbols in the data stream. The receiver uses these pilot symbols to derive its amplitude and phase reference. Optimum frame synchronization techniques are used to develop two synchronizers for PSAM systems; one is based on a standard maximum likelihood estimation formulation and the other is a sequential testing algorithm. Both methods use a simple quadratic correlation filter with an energy correction factor. Finally, it is shown that these pilots can be used to estimate the frequency mismatch between the transmitter and receiver. In all problems, both a theoretical performance analysis and Monte Carlo simulations are used to verify the algorithms.
Degree
Ph.D.
Advisors
Krogmeier, Purdue University.
Subject Area
Electrical engineering
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