Linearization of M-LINC Systems Using GMP and Particle Swarm Optimization for Wireless Communications

Document Type : Research Article


1 Electrical Engineering Department, Amirkabir University of Technology, Tehran, Iran

2 Department of Electrical and Computer engineering, University of Kashan, Kashan, Iran


In this paper, an efficient algorithm for the efficiency maximization of the multilevel linear amplification using nonlinear components (M-LINC) systems is proposed regarding the linearity of the system. In this algorithm, we use the generalized memory polynomial (GMP) to provide a behavioral model for the power amplifier (PA) and calculate the power spectral density (PSD) of the output signal of the system instead of using complicated analytical methods or time-consuming circuit level simulations. In order to have a reliable model, a modeling process which validates the static and dynamic behaviors of the obtained model is provided, and the validation is performed through the time domain signals, PSD, and AM-AM characteristics. As an example, we optimize the efficiency of a 6 level LINC system with a 2.4 GHz 25 W Doherty PA and a 15 MHz three-tone signal using the particle swarm optimization (PSO) method where an upper bound on the adjacent channel leakage ratio (ACLR) is considered as the linearity constraint. Our results show that for each given ACLR limit by a communication standard, the efficiency can be maximized with a certain number of levels in M-LINC system. Furthermore, the results unveil the trade-off between linearity and efficiency in M-LINC systems.


dor 20.1001.1.25882953.2019.

Main Subjects

[1] J. Joung, C.K. Ho, S. Sun, Spectral efficiency and energy efficiency of OFDM systems: Impact of power amplifiers and countermeasures, IEEE Journal on selected areas in communications, 32(2) (2013) 208-220.
[2] N.N. Moghadam, G. Fodor, M. Bengtsson, D.J. Love, On the Energy Efficiency of MIMO Hybrid Beamforming for Millimeter-Wave Systems With Nonlinear Power Amplifiers, IEEE Transactions on Wireless Communications, 17(11) (2018) 7208-7221.
[3] T. Qi, S. He, Power Up Potential Power Amplifier Technologies for 5G Applications, IEEE Microwave Magazine, 20(6) (2019) 89-101.
[4] M. Litchfield, T. Cappello, The Various Angles of Outphasing PAs: Competitiveness of Outphasing in Efficient Linear PA Applications, IEEE Microwave Magazine, 20(4) (2019) 135-145.
[5] T. Barton, Not just a phase: Outphasing power amplifiers, IEEE Microwave Magazine, 17(2) (2016) 18-31.
[6] K.-Y. Jheng, Y.-J. Chen, A.-Y. Wu, Multilevel LINC system designs for power efficiency enhancement of transmitters, IEEE Journal of selected topics in Signal Processing, 3(3) (2009) 523-532.
[7] P.A. Godoy, S. Chung, T.W. Barton, D.J. Perreault, J.L. Dawson, A 2.4-GHz, 27-dBm asymmetric multilevel outphasing power amplifier in 65-nm CMOS, IEEE Journal of Solid-State Circuits, 47(10) (2012) 2372-2384.
[8] A.D. Pham, Outphase power amplifiers in OFDM systems, Ph. D. dissertation, MIT, 2005.
[9] T.W. Barton, D.J. Perreault, Theory and implementation of RF-input outphasing power amplification, IEEE Transactions on Microwave Theory and Techniques, 63(12) (2015) 4273-4283.
[10] H. Moazzen, A. Mohammadi, R. Mirzavand, Multilevel outphasing system using six-port modulators and Doherty power amplifiers, Analog Integrated Circuits and Signal Processing, 90(2) (2017) 361-372.
[11] M. Majidi, A. Mohammadi, A. Abdipour, Accurate analysis of spectral regrowth of nonlinear power amplifier driven by cyclostationary modulated signals, Analog Integrated Circuits and Signal Processing, 74(2) (2013) 425-437.
[12] M. Baghani, A. Mohammadi, M. Majidi, M. Valkama, Analysis and rate optimization of OFDM-based cognitive radio networks under power amplifier nonlinearity, IEEE Transactions on Communications, 62(10) (2014) 3410-3419.
[13] S.A. Maas, Nonlinear microwave and RF circuits, Artech house, 2003.
[14] A. Vaezi, A. Abdipour, A. Mohammadi, F.M. Ghannouchi, On the modeling and compensation of backward crosstalk in MIMO transmitters, IEEE Microwave and Wireless Components Letters, 27(9) (2017) 842-844.
[15] D.R. Morgan, Z. Ma, J. Kim, M.G. Zierdt, J. Pastalan, A generalized memory polynomial model for digital predistortion of RF power amplifiers, IEEE Transactions on signal processing, 54(10) (2006) 3852-3860.
[16] H. Hemesi, A. Abdipour, A. Mohammadi, Analytical modeling of MIMO-OFDM system in the presence of nonlinear power amplifier with memory, IEEE Transactions on Communications, 61(1) (2012) 155-163.
[17] O. Bretscher, Linear Algebra with Applications 2e, in, Prentice-Hall, 2001.
[18] M.H. Gruber, Statistical digital signal processing and modeling, in, Taylor & Francis Group, 1997.
[19] M. Baghani, A. Mohammadi, M. Majidi, Downlink resource allocation in OFDMA wireless networks under power amplifier non-linearity, IET Communications, 11(18) (2017) 2751-2757.
[20] S. Scott-Hayward, E. Garcia-Palacios, Channel time allocation PSO for gigabit multimedia wireless networks, IEEE Transactions on multimedia, 16(3) (2014) 828-836.
[21] M. Bakr, Nonlinear Optimization in Electrical Engineering with Applications in MATLAB®, Institution of Engineering and Technology, 2013.
[22] J. Guan, X.A. Nghiem, A.F. Aref, R. Negra, Impact of dispersion caused by bandwidth limitation on the linearity of multilevel LINC transmitters, in: 2014 44th European Microwave Conference, IEEE, 2014, pp. 1309-1312.
[23] M. Martelius, K. Stadius, J. Lemberg, T. Nieminen, E. Roverato, M. Kosunen, J. Ryynänen, L. Anttila, M. Valkama, Multilevel outphasing power amplifier system with a transmission-line power combiner, in:  2016 12th Conference on Ph. D. Research in Microelectronics and Electronics (PRIME), IEEE, 2016, pp. 1-4.
[24] T. Cappello, T.W. Barton, C. Florian, M. Litchfield, Z. Popovic, Multilevel supply-modulated Chireix outphasing with continuous input modulation, IEEE Transactions on Microwave Theory and Techniques, 65(12) (2017) 5231-5243.