Space -Time Transmit Precoding and Interference Suppression for a Wireless Downlink

The first topic considered in the thesis is interference suppression using space-time transmit filters for a multiuser system, assuming perfect channel feedback. The filter design is formulated as an optimization problem, and an iterative algorithm that converges to the global optimum is derived. Next, the effect of imperfections in the channel feedback is investigated, focusing on a single receiver. Conditioned on the feedback, the space-time channel estimate at the transmitter is modeled as a random vector with a complex Gaussian distribution, which is consistent with standard models of Rayleigh and Rician fading channels. Optimum strategies that maximize the long term information transfer rate are derived under a variety of assumptions regarding this distribution. It is shown that the simple strategy of beamforming is close to optimal in many situations of interest. Finally, methods for the generation of channel feedback are devised. These methods employ Wiener filtering at the transmitter and the receiver for channel estimation and prediction from information derived from the pilot and feedback, respectively. Furthermore, these schemes employ the novel approach of directly sending analogue values back to the transmitter, thus avoiding quantization error. The new schemes are shown to provide better channel estimates than quantization-based feedback schemes currently being standardized for third generation cellular systems.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Visotsky, Eugene

Contributors dc:contributor

• Upamanyu Madhow

• Engineering, Electronics and Electrical

Language dc:language

eng

Identifier

(MiAaPQ)AAI3017008

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/80700