Publication:
Effect of Doppler shift on adaptive OFDM modulation for cognitive radio application

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Authors
Ahn, Byunghyun
Subjects
Cognitive Radio (CR)
Signal-to-Noise Ratio (SNR)
Signal-to-Interference Ratio (SIR)
Adaptive Orthogonal Frequency Division Multiplexing (AOFDM)
Frequency Offset
Doppler shift
Quadrature Phase Shift Keying (QPSK)
Quadrature Amplitude Modulations (QAM)
Subcarrier Allocation Scheme
Advisors
Romero, Ric A.
Ha, Tri T.
Su, Weilian
Date of Issue
2013-12
Date
Dec-13
Publisher
Monterey, California: Naval Postgraduate School
Language
Abstract
In this thesis, the effect of Doppler shift on adaptive orthogonal frequency-division multiplex (OFDM) modulation in a cognitive radio (CR) application is investigated. We present Monte Carlo simulations of OFDM modulation in which a group or groups of subcarriers are modulated using quadrature phase-shift keying (QPSK) modulation and 16-ary quadrature amplitude modulations (16QAM). We show that turning off some subcarriers does not affect the performance as long as the effective Eb/No remains the same. We also present Monte Carlo simulations where the power ratio of two sets of subcarriers is changed while maintaining the same total power in order to investigate the effect on performance. Finally, we consider a two-user CR scenario and investigate the performance effect on a primary user by a secondary user in terms of various Doppler shift offsets where both the primary user and secondary user use OFDM modulations.
Type
Thesis
Description
Series/Report No
Department
Electrical and Computer Engineering
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NPS Report Number
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Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.
Copyright is reserved by the copyright owner.
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