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A robust cogntive radio based adaptive frequency/time spreading for OFDM systems

Title
A robust cogntive radio based adaptive frequency/time spreading for OFDM systems
Authors
Kim M.-R.Kim E.Park J.-I.Kim N.-M.
Ewha Authors
김낙명
SCOPUS Author ID
김낙명scopus
Issue Date
2006
Journal Title
IEEE Vehicular Technology Conference
ISSN
1550-2252JCR Link
Citation
pp. 652 - 656
Indexed
SCOPUS scopus
Abstract
The cognitive radio (CR) technology is an effective technology for a flexible use of the radio spectrum. However, the interference between the primary and the CR users becomes a critical problem for the CR system. In this paper, we propose a cognitive radio based adaptive frequency/time spreading for the orthogonal frequency division multiplexing (OFDM) systems. This new approach is characterized by the adaptive frequency spreading and time spreading, and the adaptive power control of the subcarriers at the borders of the CR user's spectrum. Specifically, we propose a frequency spreading scheme according to the amount of the adjacent channel interference (ACI) coming from nearby primary users, which improves the power gain of data under severe interference. On the other hand, in order not to give an excessive interference the primary system, we also propose to reduce the power of the subcarriers near the edges of the bandwidth by spreading the signal in time. By the computer simulation, it has been proved that the proposed CR based OFDM system is very robust against ACI in comparison with the conventional OFDM system having adaptive guard bands. We also confirmed that the performance of the primary user is maintained with only a nominal degradation in the coexistence environment of the primary and CR system. © 2006 IEEE.
DOI
10.1109/VTCF.2006.143
ISBN
1424400635; 9781424400638
Appears in Collections:
엘텍공과대학 > 전자공학과 > Journal papers
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