Robust Precoder Design in Wireless Networks

  • The ever shrinking cell sizes to accommodate more users make the performance of wireless cellular networks interference limited. To mitigate inter-cell interference in downlink transmissions, many researchers have studied coordinated signal processing across base stations assuming perfect channel knowledge at the transmitter side. This unrealistic assumption necessitates the development of robust multi-cell precoding techniques to cope with channel estimation errors and quantization errors in practical transmission. In existing literature, robust precoder designs for single-cell downlink transmissions have been extensively investigated, where intercell interference was treated as background noise. However, robust multi-cell signal processing has not been adequately explored. The main focus of this thesis is to develop a framework to design robust precoders for various wireless networks with different kinds of channel models. Specifically, we consider both worst-case and stochastic approaches for multiple-input-single-output (MISO) systems. In the first part of the thesis, worst-case approach that is suitable to account for quantization errors is employed. Initially, robust precoders are designed applying semidefinite relaxation (SDR) techniques for amplify-and-forward (AF) networks. Later, we apply more sophisticated techniques via S-procedure to develop robust beamformers for multi-cell networks. It is also shown that the developed methods can be easily extended to multi-cell cognitive radio (CR) networks. In the second half, the probabilistic approach to accommodate channel estimation errors is considered. Conservative bounds to the optimal objective are derived and efficiently solved via convex optimization methods. The proposed algorithms that can be efficiently computed either solve uninvestigated problems or provide improved performance as compared to the existing state- of-the-art techniques.

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Publishing Institution:IRC-Library, Information Resource Center der Jacobs University Bremen
Granting Institution:Jacobs Univ.
Author:Dhananjaya Sarma Ponukumati
Referee:Feifei Gao, Jon Wallace, Wei Liu
Advisor:Feifei Gao
Persistent Identifier (URN):urn:nbn:de:101:1-201305294596
Document Type:PhD Thesis
Date of Successful Oral Defense:2012/07/18
Date of First Publication:2012/07/30
PhD Degree:Electrical Engineering
School:SES School of Engineering and Science
Library of Congress Classification:T Technology / TK Electrical engineering. Electronics. Nuclear engineering / TK5101-6720 Telecommunication. Including telegraphy, telephone, radio, radar, television [and positioning technology] / TK5101-5105.8887 Telecommunication / TK5103.2-5103.4885 Wireless communication systems. Mobile communication systems
Call No:Thesis 2012/21

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