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Download fileCombating Nonlinear Power Amplifier Effects in Multicarrier Systems
thesis
posted on 2014-06-20, 00:00 authored by Guoguang ChenMulticarrier modulation is widely accepted as a powerful technology to satisfy the increasing
demand of high data rate transmission. The inherent large envelope fluctuations of multicarrier
signals necessitate the use of power amplifiers (PA) with large dynamic range. However, the
incompatibility between linear amplification and power efficiency poses challenges in deployment
of practical wireline or wireless systems. When high power efficiency is mandatory, nonlinear
power amplifier effects are inevitable and thus system performance is degraded.
In this dissertation, several novel methods based on signal design and processing techniques
are proposed to combat nonlinear power amplifier effects in multicarrier systems, specifically
focusing on boosting power efficiency and improving bit error rate in orthogonal frequency
division multiplexing (OFDM) and multiple access OFDM (OFDMA).
First, with emphasis on easy implementation and low cost at the transmitter, two novel peak
windowing schemes, with asymmetric window functions and simple coefficient optimization
respectively, are proposed to handle the case of successive peaks in transmitted signals, which
outperform existing methods. In addition, a novel receiver-oriented method is proposed to
tackle the intrinsic challenge in OFDMA reception where an individual user has insufficient
information of other users’ modulation to apply conventional decision-aided schemes. The
proposed method includes two steps: improved peak localization and magnitude estimation
with frame based alternating projection which does not require modulation information of
the entire OFDM symbol, and has significantly enhanced performance compared with existing
schemes, especially in the high signal-to-noise regime. Furthermore, we propose a joint design
of transmitter-oriented scheme of tone reservation with clipping and receiver-oriented scheme
of frame-based alternating projection which opens up a novel way to deal with the nonlinear
power amplifier effects. The tight requirement of sparsity level in clipping noise imposed by
compressed sensing framework is relaxed with the novel formulation based on frame theory
and projection over convex sets and thus significant bit error rate performance improvement
is achieved. Moreover, a hybrid scheme that combines two existing single-antenna schemes,
namely erasure pattern selection and Fourier projection algorithm, is designed to address the
issue for the multi-antenna case and simulations demonstrate it outperforms a popular existing
scheme.
History
Advisor
Ansari, RashidDepartment
Electrical and Computer EngineeringDegree Grantor
University of Illinois at ChicagoDegree Level
- Doctoral
Committee Member
Zefran, Milos Ben-Arie, Jezekiel Tuninetti, Daniela Kshemkalyani, AjaySubmitted date
2014-05Language
- en
Issue date
2014-06-20Usage metrics
Categories
No categories selectedKeywords
power efficiencyPeak-to-Average Power Ratio (PAPR)Orthogonal Frequency Division Multiplexing (OFDM)Orthogonal Frequency Division Multiple Access (OFDMA)peak windowingFrame-based Alternating ProjectionProjection Over Convex Sets (POCS)frame theoryMultiple Input Multiple Output-Orthogonal Frequency Division Multiplexing (MIMO-OFDM)