An adaptive polarization-QAM modulation scheme for improving the power amplifier energy efficiency in OFDM systems

To improve the energy efficiency of power amplifier in OFDM systems, an adaptive polarization-QAM modulation scheme is proposed considering the data rate requirement variation at the transmitter. Since QAM and polarization modulation have different energy efficiency performance in the linear and non...

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Bibliographic Details
Main Authors: Shulun Zhao, Zhimin Zeng, Chunyan Feng, Fangfang Liu, Yao Nie
Format: Conference Proceeding
Language:English
Subjects:
Adaptation models
adaptive polarization-QAM modulation
Data models
energy efficiency
Nonlinear distortion
OFDM
OFDM systems
power amplifier nonlinearity
Quadrature amplitude modulation
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Summary:To improve the energy efficiency of power amplifier in OFDM systems, an adaptive polarization-QAM modulation scheme is proposed considering the data rate requirement variation at the transmitter. Since QAM and polarization modulation have different energy efficiency performance in the linear and nonlinear region of power amplifier respectively, thus the optimal energy efficiency can be obtained by combining the two modulation schemes together and adjusting their modulation order adaptively to fulfill the varying data rate requirement. The power series model of power amplifier is used to analyze the effects of both the in-band distortions and the out-of-band emissions on OFDM signals. Based on above, the proposed scheme can be formulated as an optimization problem regarding the output back off value as well as the modulation order of polarization modulation and QAM. Simulations under the same symbol error rate threshold and data rate requirement show that, the energy efficiency of the proposed scheme is nearly twice as that of the traditional QAM scheme in OFDM systems.
ISSN:2166-9589
DOI:10.1109/PIMRC.2016.7794638