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Dissertations and Theses Dissertations and Theses
Spring 3-30-2018
Power Spectrum Prediction of Ampli<ed Dual-Band Power Spectrum Prediction of Ampli<ed Dual-Band
LTE-Advanced Signals LTE-Advanced Signals
Xianzhen Yang
Portland State University
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Recommended Citation Recommended Citation
Yang, Xianzhen, "Power Spectrum Prediction of Ampli<ed Dual-Band LTE-Advanced Signals" (2018).
Dissertations and Theses.
Paper 4351.
https://doi.org/10.15760/etd.6244
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Power Spectrum Prediction of Amplified Dual-Band LTE-Advanced Signals
by
Xianzhen Yang
A thesis submitted in partial fulfillment of the
requirements for the degree of
Master of Science
in
Electrical and Computer Engineering
Thesis Committee:
Fu Li, Chair
James Morris
Xiaoyu Song
Portland State University
2018
© 2018 Xianzhen Yang
i
Abstract
In wireless communication, the nonlinearity of a radio frequency (RF) power amplifier is
an important issue for power amplifier designers. Since the nonlinearity is generated by
the properties of physical components, it is hard to avoid it in producing power
amplifiers. Power amplifier designers should know about the nonlinearity in order to
compensate for it.
A two-tone test is a relatively widely used method to measure the nonlinearity of a power
amplifier, which means the third order intercept point (IP3) can be measured from the
two-tone test. Through the two-tone test, researchers have proposed some formulae to
present what the amplified Code Division Multiple Access (CDMA) signal is like. They
derived formulae in terms of output power, bandwidth, IP3, and IP5 to express the
amplified CDMA signal and further to Orthogonal Frequency Division Multiplexing
(OFDM) signals. With the development of wireless communication, researchers put their
interest increasingly in Multiple Input Multiple Output (MIMO) systems. A formula
expressing amplified dual two-tone signals has been proposed. In their research, they
discussed what the expressions of intermodulation and cross modulation are and what
their locations are.
In this research, dual band LTE-Advanced signals, whose modulation is OFDM are
utilized, which means this research proposes a formula expression about the power
spectrum of dual-band LTE-Advanced signals. Intermodulation and cross modulation
caused by nonlinearity of power amplifiers are then specially discussed. This study will
help RF designers to continuously compensate for them.
ii
Table of contents
Abstract ............................................................................................................................................. i
List of figures .................................................................................................................................. iii
Chapter 1 Introduction ..................................................................................................................... 1
Chapter 2 Spectrum Model of Dual-Band LTE-Advanced Signals ................................................. 4
2.1 Statistical Model of LTE-Advanced Signals ......................................................................... 4
2.2 The Nonlinear Model and Parameters of RF Power Amplifiers (PAs).................................. 5
2.3 Correlation of the Dual-Band LTE-Advanced Output Signals .............................................. 6
2.4 The PSD of Amplified Dual-Band LTE-Advanced Output Signals .................................... 16
Chapter 3 Experimental Verification ............................................................................................. 25
Chapter 4 Conclusion ..................................................................................................................... 27
Reference ....................................................................................................................................... 28
Appendix ........................................................................................................................................ 29
Appendix A The calculation of mathematical expectation
12
( ) ( )E s t s t
. ........................ 29
Appendix B Derivation of mathematical expectation
32
1 1 2
( ) ( ) ( )E s t s t s t
,
23
1 2 1
( ) ( ) ( )E s t s t s t
, and
22
1 2 1 2
{ ( ) ( ) ( ) ( )}E s t s t s t s t
. ................................................ 32
Appendix C Derivation of
1
3
()
s
R
and
12
2
( ) ( )
ss
RR
.................................................... 37
Appendix D Derivation of
1
()
y
Pf
in the condition of
12
2BB
............................................. 41
Appendix E Derivation of
1
()
y
Pf
............................................................................................. 44
