The original paper is in English. Non-English content has been machine-translated and may contain typographical errors or mistranslations. ex. Some numerals are expressed as "XNUMX".
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The original paper is in English. Non-English content has been machine-translated and may contain typographical errors or mistranslations. Copyrights notice
Dans cet article, une technique de suppression des lobes secondaires pour les radios cognitives (CR) basées sur le multiplexage par répartition orthogonale de la fréquence (OFDM) est proposée. Dans les systèmes CR basés sur OFDM, après que le terminal CR a exécuté la détection de spectre, il transmet un paquet CR en activant les sous-porteuses dans les bandes de fréquences où aucun signal n'est détecté (ci-après, ces sous-porteuses sont appelées « sous-porteuses actives ») et en désactivant ( annulation) les sous-porteuses dans les bandes de fréquences où les signaux sont détectés. Dans cette situation, un problème se pose dans la mesure où les signaux qui s'échappent des sous-porteuses actives vers les sous-porteuses nulles peuvent interférer avec les systèmes primaires. Il faut donc minimiser cette fuite de signal. Dans de nombreux systèmes de communication sans fil basés sur l'OFDM, un paquet ou une trame est constitué de plusieurs symboles OFDM et la discontinuité entre les symboles OFDM consécutifs provoque une fuite de signal vers les sous-porteuses nulles. Dans le procédé proposé, la fuite de signal vers les sous-porteuses nulles est supprimée en régénérant les sous-porteuses nulles dans le signal du domaine fréquentiel de l'ensemble du paquet, comme suit. Un paquet CR constitué de multiples symboles OFDM ayant des sous-porteuses nulles et un intervalle de garde (GI) est mis en mémoire tampon et suréchantillonné, puis le signal suréchantillonné est transformé de Fourier en une seule fois et, par conséquent, le signal dans le domaine fréquentiel du paquet est obtenu. Les sous-porteuses nulles dans le signal dans le domaine fréquentiel sont à nouveau remises à zéro, puis le signal est transformé et transmis par transformation de Fourier inverse. La méthode proposée supprime considérablement la fuite de signal. La densité spectrale de puissance, le rapport de puissance crête à moyenne (PAPR) et les performances du taux d'erreur sur les paquets (PER) de la méthode proposée sont évalués par des simulations informatiques et l'efficacité de la méthode proposée est démontrée.
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Tomoya TANDAI, Takahiro KOBAYASHI, "A Sidelobe Suppression Technique by Regenerating Null Signals in OFDM-Based Cognitive Radios" in IEICE TRANSACTIONS on Communications,
vol. E92-B, no. 12, pp. 3653-3664, December 2009, doi: 10.1587/transcom.E92.B.3653.
Abstract: In this paper, a sidelobe suppression technique for orthogonal frequency division multiplexing (OFDM)-based cognitive radios (CR) is proposed. In the OFDM-based CR systems, after the CR terminal executes spectrum sensing, it transmits a CR packet by activating the subcarriers in the frequency bands where no signals are detected (hereinafter, these subcarriers are called "active subcarrier") and by disabling (nulling) the subcarriers in the frequency bands where the signals are detected. In this situation, a problem arises in that the signals that leak from the active subcarriers to the null subcarriers may interfere with the primary systems. Therefore, this signal leakage has to be minimized. In many OFDM-based wireless communication systems, one packet or frame consists of multiple OFDM symbols and the discontinuity between the consecutive OFDM symbols causes the signal leakage to the null subcarriers. In the proposed method, signal leakage to the null subcarriers is suppressed by regenerating null subcarriers in the frequency-domain signal of the whole packet as follows. One CR packet consisting of multiple OFDM symbols having null subcarriers and guard interval (GI) is buffered and oversampled, and then the oversampled signal is Fourier transformed at once and consequently the frequency-domain signal of the packet is obtained. The null subcarriers in the frequency-domain signal are zeroed again, and then the signal is inverse Fourier transformed and transmitted. The proposed method significantly suppresses the signal leakage. The spectral power density, the peak-to-average power ratio (PAPR) and the packet error rate (PER) performances of the proposed method are evaluated by computer simulations and the effectiveness of the proposed method is shown.
URL: https://global.ieice.org/en_transactions/communications/10.1587/transcom.E92.B.3653/_p
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@ARTICLE{e92-b_12_3653,
author={Tomoya TANDAI, Takahiro KOBAYASHI, },
journal={IEICE TRANSACTIONS on Communications},
title={A Sidelobe Suppression Technique by Regenerating Null Signals in OFDM-Based Cognitive Radios},
year={2009},
volume={E92-B},
number={12},
pages={3653-3664},
abstract={In this paper, a sidelobe suppression technique for orthogonal frequency division multiplexing (OFDM)-based cognitive radios (CR) is proposed. In the OFDM-based CR systems, after the CR terminal executes spectrum sensing, it transmits a CR packet by activating the subcarriers in the frequency bands where no signals are detected (hereinafter, these subcarriers are called "active subcarrier") and by disabling (nulling) the subcarriers in the frequency bands where the signals are detected. In this situation, a problem arises in that the signals that leak from the active subcarriers to the null subcarriers may interfere with the primary systems. Therefore, this signal leakage has to be minimized. In many OFDM-based wireless communication systems, one packet or frame consists of multiple OFDM symbols and the discontinuity between the consecutive OFDM symbols causes the signal leakage to the null subcarriers. In the proposed method, signal leakage to the null subcarriers is suppressed by regenerating null subcarriers in the frequency-domain signal of the whole packet as follows. One CR packet consisting of multiple OFDM symbols having null subcarriers and guard interval (GI) is buffered and oversampled, and then the oversampled signal is Fourier transformed at once and consequently the frequency-domain signal of the packet is obtained. The null subcarriers in the frequency-domain signal are zeroed again, and then the signal is inverse Fourier transformed and transmitted. The proposed method significantly suppresses the signal leakage. The spectral power density, the peak-to-average power ratio (PAPR) and the packet error rate (PER) performances of the proposed method are evaluated by computer simulations and the effectiveness of the proposed method is shown.},
keywords={},
doi={10.1587/transcom.E92.B.3653},
ISSN={1745-1345},
month={December},}
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TY - JOUR
TI - A Sidelobe Suppression Technique by Regenerating Null Signals in OFDM-Based Cognitive Radios
T2 - IEICE TRANSACTIONS on Communications
SP - 3653
EP - 3664
AU - Tomoya TANDAI
AU - Takahiro KOBAYASHI
PY - 2009
DO - 10.1587/transcom.E92.B.3653
JO - IEICE TRANSACTIONS on Communications
SN - 1745-1345
VL - E92-B
IS - 12
JA - IEICE TRANSACTIONS on Communications
Y1 - December 2009
AB - In this paper, a sidelobe suppression technique for orthogonal frequency division multiplexing (OFDM)-based cognitive radios (CR) is proposed. In the OFDM-based CR systems, after the CR terminal executes spectrum sensing, it transmits a CR packet by activating the subcarriers in the frequency bands where no signals are detected (hereinafter, these subcarriers are called "active subcarrier") and by disabling (nulling) the subcarriers in the frequency bands where the signals are detected. In this situation, a problem arises in that the signals that leak from the active subcarriers to the null subcarriers may interfere with the primary systems. Therefore, this signal leakage has to be minimized. In many OFDM-based wireless communication systems, one packet or frame consists of multiple OFDM symbols and the discontinuity between the consecutive OFDM symbols causes the signal leakage to the null subcarriers. In the proposed method, signal leakage to the null subcarriers is suppressed by regenerating null subcarriers in the frequency-domain signal of the whole packet as follows. One CR packet consisting of multiple OFDM symbols having null subcarriers and guard interval (GI) is buffered and oversampled, and then the oversampled signal is Fourier transformed at once and consequently the frequency-domain signal of the packet is obtained. The null subcarriers in the frequency-domain signal are zeroed again, and then the signal is inverse Fourier transformed and transmitted. The proposed method significantly suppresses the signal leakage. The spectral power density, the peak-to-average power ratio (PAPR) and the packet error rate (PER) performances of the proposed method are evaluated by computer simulations and the effectiveness of the proposed method is shown.
ER -