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Band Emission

The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform

I-tai Lu – 1st expert on this subject based on the ideXlab platform

  • Out-of-Band Emission suppression techniques based on a generalized OFDM framework
    EURASIP Journal on Advances in Signal Processing, 2014
    Co-Authors: Juan Fang, I-tai Lu

    Abstract:

    Orthogonal frequency division multiplexing (OFDM)-based cognitive radio (CR) systems suffer from the large out-of-Band Emission (OOBE) that may interfere with other users. Since most existing OFDM OOBE suppression schemes are derived on the base of an original OFDM system without any other scheme, we first propose a generalized OFDM framework that is capable of describing these schemes no matter whether any one or more of the schemes is applied. Then, according to the place where these schemes are implemented in our framework, they are classified into three groups, namely symbol mapping techniques, precoding techniques, and time-domain techniques. Finally, based on the proposed framework, we propose three new schemes by combining a precoding scheme named singular value decomposition (SVD) precoding with three other schemes from the three groups, namely spectral precoding, N-continuous symbol mapping, and filtering. Numerical results show the power spectral density (PSD), peak-to-average power ratio (PAPR), and bit error rate (BER) performances of the three proposed schemes. Since the individual schemes have complementary characteristics, the three proposed combined schemes are constructed to maintain the merits and avoid the drawbacks of the individual schemes involved. Thus, it is demonstrated that the proposed framework can be employed to develop other new combined OOBE suppression schemes tailoring to some specific practical needs.

  • Precoder designs for jointly suppressing out-of-Band Emission and peak-to-average power ratio in an orthogonal frequency division multiplexing system
    IET Communications, 2014
    Co-Authors: Juan Fang, I-tai Lu

    Abstract:

    High peak-to-average-ratio (PAPR) and large out-of-Band Emission (OOBE) are the two main shortcomings of orthogonal frequency division multiplexing (OFDM) signals for cognitive radios. Among all the existing techniques, it has been shown that precoding is an effective way for either reducing the PAPR or suppressing the OOBE. However, no work has focused on designing an effective precoding approach to reduce the PAPR and suppress the OOBE simultaneously. In this study, three new precoding approaches that can jointly suppress OOBE and reduce PAPR simultaneously are presented. The simulation results show that, firstly, all the three proposed precoding approaches can achieve the same power spectral density performance as the typical OOBE-suppression precoding approach with the same spectral efficiency. Secondly, their PAPR performances are only slightly worse than the typical PAPR-reduction precoding approach with a similar computational complexity. Finally, two of the three proposed precoding approaches do not cause any bit error rate (BER) performance degradation with respect to the conventional OFDM system. The abilities to suppress OOBE and PAPR jointly and to maintain the good BER performance make two of the three proposed approaches very favourable for practical applications.

  • MILCOM – Resource Block Based Precoding Schemes for Suppressing Out-of-Band Emission
    MILCOM 2013 – 2013 IEEE Military Communications Conference, 2013
    Co-Authors: Juan Fang, I-tai Lu, Jialing Li, Rui Yang

    Abstract:

    Orthogonal Frequency Division Multiplexing (OFDM) systems suffer from large out-of-Band Emission (OOBE). As one of the approaches to suppress the OOBE, the precoding technique is able to achieve significant OOBE suppression with a small spectral efficiency loss and does not depend on the input data. In this paper, a low-complexity individual precoded OFDM (I-P-OFDM) by precoding each contiguous frequency Band independently is presented. Furthermore, two resource block (RB) based precoding schemes, namely, the U-RB-P-OFDM and NU-RB-P-OFDM are presented. The RB structures utilized in these two schemes enables mitigation of the precoding matrix dependency on the spectrum allocation. Numerical results show that all three schemes can achieve satisfying spectrum containment without any degradation in BER performance, and provide various tradeoffs between spectral efficiency, computational complexity, and PAPR performance.

Juan Fang – 2nd expert on this subject based on the ideXlab platform

  • Out-of-Band Emission suppression techniques based on a generalized OFDM framework
    EURASIP Journal on Advances in Signal Processing, 2014
    Co-Authors: Juan Fang, I-tai Lu

    Abstract:

    Orthogonal frequency division multiplexing (OFDM)-based cognitive radio (CR) systems suffer from the large out-of-Band Emission (OOBE) that may interfere with other users. Since most existing OFDM OOBE suppression schemes are derived on the base of an original OFDM system without any other scheme, we first propose a generalized OFDM framework that is capable of describing these schemes no matter whether any one or more of the schemes is applied. Then, according to the place where these schemes are implemented in our framework, they are classified into three groups, namely symbol mapping techniques, precoding techniques, and time-domain techniques. Finally, based on the proposed framework, we propose three new schemes by combining a precoding scheme named singular value decomposition (SVD) precoding with three other schemes from the three groups, namely spectral precoding, N-continuous symbol mapping, and filtering. Numerical results show the power spectral density (PSD), peak-to-average power ratio (PAPR), and bit error rate (BER) performances of the three proposed schemes. Since the individual schemes have complementary characteristics, the three proposed combined schemes are constructed to maintain the merits and avoid the drawbacks of the individual schemes involved. Thus, it is demonstrated that the proposed framework can be employed to develop other new combined OOBE suppression schemes tailoring to some specific practical needs.

  • Precoder designs for jointly suppressing out-of-Band Emission and peak-to-average power ratio in an orthogonal frequency division multiplexing system
    IET Communications, 2014
    Co-Authors: Juan Fang, I-tai Lu

    Abstract:

    High peak-to-average-ratio (PAPR) and large out-of-Band Emission (OOBE) are the two main shortcomings of orthogonal frequency division multiplexing (OFDM) signals for cognitive radios. Among all the existing techniques, it has been shown that precoding is an effective way for either reducing the PAPR or suppressing the OOBE. However, no work has focused on designing an effective precoding approach to reduce the PAPR and suppress the OOBE simultaneously. In this study, three new precoding approaches that can jointly suppress OOBE and reduce PAPR simultaneously are presented. The simulation results show that, firstly, all the three proposed precoding approaches can achieve the same power spectral density performance as the typical OOBE-suppression precoding approach with the same spectral efficiency. Secondly, their PAPR performances are only slightly worse than the typical PAPR-reduction precoding approach with a similar computational complexity. Finally, two of the three proposed precoding approaches do not cause any bit error rate (BER) performance degradation with respect to the conventional OFDM system. The abilities to suppress OOBE and PAPR jointly and to maintain the good BER performance make two of the three proposed approaches very favourable for practical applications.

  • MILCOM – Resource Block Based Precoding Schemes for Suppressing Out-of-Band Emission
    MILCOM 2013 – 2013 IEEE Military Communications Conference, 2013
    Co-Authors: Juan Fang, I-tai Lu, Jialing Li, Rui Yang

    Abstract:

    Orthogonal Frequency Division Multiplexing (OFDM) systems suffer from large out-of-Band Emission (OOBE). As one of the approaches to suppress the OOBE, the precoding technique is able to achieve significant OOBE suppression with a small spectral efficiency loss and does not depend on the input data. In this paper, a low-complexity individual precoded OFDM (I-P-OFDM) by precoding each contiguous frequency Band independently is presented. Furthermore, two resource block (RB) based precoding schemes, namely, the U-RB-P-OFDM and NU-RB-P-OFDM are presented. The RB structures utilized in these two schemes enables mitigation of the precoding matrix dependency on the spectrum allocation. Numerical results show that all three schemes can achieve satisfying spectrum containment without any degradation in BER performance, and provide various tradeoffs between spectral efficiency, computational complexity, and PAPR performance.

Young Rag Do – 3rd expert on this subject based on the ideXlab platform

  • surface plasmon enhanced Band Emission of zno nanoflowers decorated with au nanoparticles
    Chemistry: A European Journal, 2012
    Co-Authors: Saji Thomas Kochuveedu, Ji Hye Oh, Young Rag Do

    Abstract:

    A simple strategy was used to enhance Band Emission through the transfer of defect Emission from ZnO to Au by using the energy match between the defect Emission of ZnO and the surface plasmon absorbance of Au NPs through decorating the surface of ZnO nanoflowers with Au nanoparticles (Au NPs). The ZnO nanostructure, which was comprised of six nanorods that were attached on one side in a flower-like fashion, was synthesized by using a hydrothermal method. The temperature-dependent morphology and detailed growth mechanism were studied. The influence of the density of the Au NPs that were deposited onto the surface of ZnO on photoluminescence was investigated to optimize the configuration of the ZnO/Au system in terms of the maximum Band Emission. The sequential transfer of defect energy from ZnO to Au and electron transfer from excited Au to ZnO was proposed as a possible mechanism for the enhanced Band Emission.