A Phase Adjustment Approach for Interference Reduction in OFDM-Based Cognitive Radios

The problem of cross-band interference in single-antenna and multi-antenna OFDM cognitive transmitters is considered. Cross-band interference, which is caused by large OFDM signal sidelobes, is a major drawback of OFDM, especially in cognitive radio applications where it is crucial to protect primar...

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Bibliographic Details
Published in:IEEE transactions on wireless communications 2013-09, Vol.12 (9), p.4668-4679
Main Authors: Alian, Ehsan Haj Mirza, Mitran, Patrick
Format: Article
Language:English
Subjects:
Antennas
Applied sciences
Cognitive radio
Complexity
Computer simulation
Detection, estimation, filtering, equalization, prediction
Exact sciences and technology
Information, signal and communications theory
Interference
interference cancellation
Mathematical analysis
Mathematical models
Multiplexing
OFDM
Orthogonal Frequency Division Multiplexing
phase adjustment
Radiocommunication specific techniques
Radiocommunications
Signal and communications theory
Signal, noise
Symbols
Telecommunications
Telecommunications and information theory
Transmitters
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Summary:The problem of cross-band interference in single-antenna and multi-antenna OFDM cognitive transmitters is considered. Cross-band interference, which is caused by large OFDM signal sidelobes, is a major drawback of OFDM, especially in cognitive radio applications where it is crucial to protect primary licensed users from the secondary user's interference. In this paper, we propose a novel low complexity technique, referred to as a phase adjustment technique, to tackle this problem in single-antenna and multi-antenna OFDM cognitive transmitters. In this technique, the phase of each OFDM symbol is adjusted in an attempt to minimize the interference caused by the secondary user to the primary. Unlike prior methods, this technique does not decrease data throughput and has no impact on the bit-error-rate and peak-to-average power ratio of the OFDM symbols. Furthermore, to calculate the adjustment phases, three heuristics, one of which is very low complexity and achieves near optimal performance in numerical simulations, are also proposed. In addition, the performance of the proposed technique is evaluated analytically in some special cases in single and multi-antenna cognitive transmitters, and is verified by numerical simulations.
ISSN:1536-1276
1558-2248
DOI:10.1109/TW.2013.072213.121994