Steady-State Performance Analysis and Step-Size Selection for LMS-Adaptive Wideband Feedforward Power Amplifier Linearizer

Balancing between power amplifier (PA) linearity and power efficiency is one of the biggest implementation challenges in radio communication transmitters. Among various linearization methods, the feedforward linearization technique is a fairly established principle offering a good tradeoff between l...

Full description

Saved in:
Bibliographic Details
Published in:IEEE transactions on signal processing 2012-01, Vol.60 (1), p.82-99
Main Authors: Gokceoglu, A., ghadam, Ali Shahed hagh, Valkama, M.
Format: Article
Language:English
Subjects:
Adaptation models
Analytical models
Applied sciences
Detection, estimation, filtering, equalization, prediction
Exact sciences and technology
Feedforward linearizer
Feedforward neural networks
Information, signal and communications theory
intermodulation distortion (IMD)
Least squares approximation
LMS
Multiplexing
OFDM
Performance analysis
power amplifier (PA)
Signal and communications theory
Signal, noise
Steady-state
step-size
Telecommunications and information theory
Wiener-Hammerstein
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Balancing between power amplifier (PA) linearity and power efficiency is one of the biggest implementation challenges in radio communication transmitters. Among various linearization methods, the feedforward linearization technique is a fairly established principle offering a good tradeoff between linearity and power-efficiency even under wideband operation. Moreover, adaptive techniques for such linearizer have been proposed in literature to track parameter changes in the main PA and other circuitry. Among those, least mean squares (LMS) method for adapting signal cancellation loop (SCL) and error cancellation loop (ECL) coefficients is an attractive low-complexity alternative. In this paper, we carry out extensive closed-form performance analysis of the achievable intermodulation distortion (IMD) reduction of the overall LMS-adaptive feedforward linearizer, as a function of the used step-sizes and essential waveform statistics. Such analysis is currently missing from the state-of-the-art literature. Both memoryless nonlinearities and Wiener-Hammerstein type PA memory models are studied for which IMD suppression expressions are derived. Comprehensive computer simulations are also provided to illustrate the accuracy of the analysis when practical OFDM waveforms are used. Design examples are given as well where the analysis results are used to choose proper linearizer step-sizes to meet given transmitter spectral mask specifications.
ISSN:1053-587X
1941-0476
DOI:10.1109/TSP.2011.2169254