Mr. Alberto Arredondo
UT Austin
Friday, May 7th, 10:00 AM, ENS 634A
In order to accomodate a greater number of users in communications systems, engineers now take advantage of the spatial separation of users as well as the separation of their transmissions in the time and frequency domain. This is called Space Division Multiple Access (SDMA). An SDMA system is essentially an array of antennas coupled to signal processing equipment which discriminates among the users which transmit on the same frequency and at the same time. In order to make this discrimination, the system must determine the spatial signature (SS) (proportional to the vector of electric fields impinging on the array) associated with each user.
The motivation for the ideas behind this work came from reading research concering the relationship between spatial signature stability and mobile user displacement. These researchers were interested in how often an observation of a spatial signature (in the uplink) must be updated since this knowledge is useful for downlink transmission. In this work, I attempt to extend the minimum time between observations by predicting the behavior of the spatial signatures themselves.
I use a black-box approach to model the spatial signature variation which allows me the freedom to treat them as, simply, a vector of complex numbers varying in time. Thus using a synthesis or prediction error filter to model or predict the SS, the problem becomes the determination of the coefficients of these filters. I present results of modeling and predicting the vector channel.
Alberto Arredondo graduated in 1994 from the University of Texas at Austin with a Bachelor of Science degree in Electrical Engineering with emphasis on electromagnetics. He earned his Master of Science degree from the University of California at Berkeley in 1996 and returned to U.T. Austin and joined Professor G. Xu's research group. He served as a technical consultant with Fulbright and Jaworski, L.L.P. from November 1998 to April 1999 in an intellectual property dispute involving IS-54 technology.
A list of Signal and Image Processing Seminars is available at from the ECE department Web pages under "Seminars". The Web address for the Signal and Image Processing Seminars is http://anchovy.ece.utexas.edu/seminars