CAREER: Time-Varying Signal Processing For Wideband Wireless Communications

Arizona State University, Scottsdale AZ

Investigators

Abstract

0134002 Papandreou-Suppappola, Antonia Arixozona State University CAREER: Time-Varying Signal Processing For Wideband Wireless Communications New and novel signal processing and communication algorithms are required to improve the performance of wireless communications systems, and to meet major challenges that arise from the escalating demand for new higher data rate wireless technologies. These challenges include methodologies to reduce channel impairments, higher data rate and higher bandwidth requirements to provide ubiquitous access, and schemes to improve multiple access transmission. As the nature of the wireless channel is time-varying, these challenges lead to many problems such as multiple access interference and fading due to time and frequency selectivity. Thus, the channel requires two-dimensional time-frequency processing methodologies especially designed to characterize spectral changes with time. Recently, the importance of time-frequency techniques in wireless communications has successfully been demonstrated for interference suppression and channel diversity. This research involves the development of novel time-frequency methods to address problems that surface due to the time-varying nature of the wireless channel. Specifically, these methodologies develop time-varying modulation schemes for code division and orthogonal frequency division multiple access systems, and investigate the effect of the schemes on fading distortions and multiple access interference. In addition, they design time-frequency transforms to enhance detection performance for multiple access systems and detection techniques for the new modulation schemes. They also utilize time-lag and frequency-lag techniques to jointly estimate multipath and Doppler fading parameters needed to improve detection performance at the receiver. Furthermore, they characterize wideband channels and employ the model to reduce fading and multiple access interference for broadband systems such as underwater or satellite wireless communications and third generation wideband systems. These research contributions impact the role and significance of time-varying signal processing in advancing knowledge to meet the high demands for wireless technological advances.