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Session: Session 18:00 AM Friday, May 28, 2010 Room: Pacific A |
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Session: Session 1 | Modulated Signals for Wireless Communications |
Chair: | John Wood, Freescale Semiconductor Inc |
Abstract: | This session provides the introduction to the topic of modulated signals for wireless communications, and their measurement. The invited keynote presentation describes the current status of the wireless communications signals, their evolution, characteristics, and measurement. The next two papers describe the measurement and correction of nonlinearities in a power amplifier using digital pre-distortion methods, and the development and characterization of multi-standard power amplifiers covering several frequency bands and modulation formats. |
| | Session 1-1 | Modern Cellular Wireless Signals | 8:00 AM-8:40 AM | E. McCune, RF Communications Consulting, Santa Clara, United States |
(50) | With the evolution of cellular wireless systems and services, the on-air signals themselves are also undergoing very significant transformations. This paper provides a survey of the active and coming-soon signal types adopted for cellular wireless systems around the world. Focus is on modulation schemes, along with various measures used to characterize the signals before and after power amplification. Cost-benefit tradeoff information is introduced to provide perspective on this signal evolution. | | |
Session 1-2 | Measurement and Correction of Residual Nonlinearities in a Digitally Predistorted Power Amplifier | 8:40 AM-9:00 AM | R. N. Braithwaite, Powerwave Technologies, Santa Ana, United States |
(11) | A reduced cost method for the measurement and correction of residual nonlinearities in a digitally predistorted transmitter is proposed. The original system uses a calibration signal applied off-line and a cancellation loop with a square law detector to measure residual nonlinearities. The approach is improved by replacing the calibration signal with the actual signal transmitted, resulting in an on-line measurement system. A further extension integrates several measurements over the input envelope range to adapt a fourth-order polynomial predistorter. Simulation results for a WCDMA input with a 101 carrier configuration show that the proposed approach for measuring residual nonlinearities and estimating predistortion coefficients is effective. | | |
Session 1-3 | Experimental Sensitivity Analysis of Multi-Standard Power Amplifiers Nonlinear Characterization under Modulated Signals | 9:00 AM-9:20 AM | M. Ben Ayed2, S. Boumaiza1, 1University of Waterloo, Waterloo, Canada, 2Ecole Polytechnique de Tunisie, Tunis, Tunisia |
(48) | This paper proposes an experimental analysis focusing on the sensitivity of three behavioral models, Memory Polynomial (MP), Augmented Hammerstein (AH) and the two hidden layers artificial neural networks (2HLANN) to the characteristics of the input signal driving the power amplifier (PA) to be linearized. The analysis is carried out by changing separately each signal characteristic, respectively the peak to average power ratio (PAPR), the Probability density function (PDF), and the modulation bandwidth and assess the sensitivity of the DPD to that change. When used to linearise a 250 Watt peak-envelop-power Doherty PA, the considered models showed relatively small sensitivity to the variation of these signal characteristics. Yet, the 2HLANN was found to be the most robust model with excellent linearization capabilities. | | |
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