The Experts below are selected from a list of 5325 Experts worldwide ranked by ideXlab platform

Iwao Sasase - One of the best experts on this subject based on the ideXlab platform.

  • transmit phase control to increase the minimum eigenvalue of the Channel Correlation Matrix in the etd system
    Electronics and Communications in Japan Part I-communications, 2007
    Co-Authors: Ryuichiro Shimura, Iwao Sasase
    Abstract:

    For conditions under which the Channel conditions between the transmitting and receiving antennas are known on the transmitter side when TDD (Time Division Duplex) is used in the MIMO (Multi-Input Multi-Output) method, much attention has been devoted to E-SDM (Eigenbeam Space Division Multiplexing), in which the influence of CCI (Co-Channel Interference) is eliminated by making the different transmission signal sequences orthogonal in space by means of the eigenvectors of the Channel Matrix used as the transmission and reception weights. However, in such a system as E-SDM, in which eigenvectors of the Channel Matrix are used, more than two antennas are needed on the receiving side in order to perform eigenvalue decomposition of the Channel Matrix. In this paper, in order to realize a system using the eigenvectors as the transmission and reception weights even in a system with two transmitting antennas and one receiving antenna under TDD, the ETD (Eigenbeam Transmit Diversity) system is proposed. In this system, the concept of frequency diversity is applied, in which identical signals are transmitted on two subcarriers on one transmitting antenna, so that a MIMO system is virtually realized with subcarriers of the OFDM (Orthogonal Frequency Division Multiplexing) in place of receiving antennas in the row direction of the Channel Matrix. In the ETD system, the minimum eigenvalue of the Channel Matrix can be made larger by adaptively interchanging the signals among antennas and by transmission phase control. Hence, the BER characteristics of the signal sequence by which the minimum eigenvalue is multiplied can be improved. The characteristics are evaluated by computer simulations. It is shown that the proposed system is superior in terms of BER characteristics to the transmission diversity system in which transmission phase control is carried out among the antennas. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(7): 38–51, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20342

  • transmit phase control to increase the minimum eigenvalue of Channel Correlation Matrix in the e sdm ofdm system
    Vehicular Technology Conference, 2004
    Co-Authors: Ryuichiro Shimura, T Ohno, T Kambayashi, Iwao Sasase
    Abstract:

    In multiple-input multiple-output (MIMO) systems, the eigen-beam space division multiplexing (E-SDM) system has been proposed for mitigating the effect of co-Channel interference (CCI). Received signal to noise ratio (SNR) in the E-SDM system depends on the eigenvalues of the Channel Correlation Matrix. Consequently, the bit error rate (BER) performance of the data stream multiplied by the minimum eigenvalue is degraded in comparison with that of another data stream. We propose an E-SDM/OFDM system to control the eigenvalues of a Channel Correlation Matrix by using transmit phase control. Computer simulation results indicate the proposed E-SDM/OFDM system with transmit phase control can improve the BER performance compared with E-SDM/OFDM system without using transmit phase control.

Xiaodong Xu - One of the best experts on this subject based on the ideXlab platform.

  • subspace based noise variance and snr estimation for mimo ofdm systems
    Journal of Electronics (china), 2006
    Co-Authors: Xiaodong Xu, Ya Jing, Junhui Zhao, Xiaohu You
    Abstract:

    This paper proposes a subspace-based noise variance and Signal-to-Noise Ratio (SNR) estimation algorithm for Multi-Input Multi-Output (MIMO) wireless Orthogonal Frequency Division Multiplexing (OFDM) systems. The special training sequences with the property of orthogonality and phase shift orthogonality are used in pilot tones to obtain the estimated Channel Correlation Matrix. Partitioning the observation space into a delay subspace and a noise subspace, we achieve the measurement of noise variance and SNR. Simulation results show that the proposed estimator can obtain accurate and real-time measurements of the noise variance and SNR for various multipath fading Channels, demonstrating its strong robustness against different Channels.

  • subspace based noise variance and snr estimation for ofdm systems mobile radio applications
    Wireless Communications and Networking Conference, 2005
    Co-Authors: Xiaodong Xu, Ya Jing, Xiaohu Yu
    Abstract:

    Noise variance and hence signal to noise ratio (SNR) estimates are very important for the Channel quality control in communication systems. Noting that in mobile communications the multipath time delays are slowly varying in time, in this paper we derive a subspace-based estimation method for orthogonal frequency division multiplexing (OFDM) systems, which is based on an eigenvector decomposition of the estimated Channel Correlation Matrix. Simulation results show that the proposed estimator can obtain accurate real time measurements of the noise variance and SNR after an observation interval of about 20 OFDM symbols for various fading Channels.

Xiaohu Yu - One of the best experts on this subject based on the ideXlab platform.

  • subspace based noise variance and snr estimation for ofdm systems mobile radio applications
    Wireless Communications and Networking Conference, 2005
    Co-Authors: Xiaodong Xu, Ya Jing, Xiaohu Yu
    Abstract:

    Noise variance and hence signal to noise ratio (SNR) estimates are very important for the Channel quality control in communication systems. Noting that in mobile communications the multipath time delays are slowly varying in time, in this paper we derive a subspace-based estimation method for orthogonal frequency division multiplexing (OFDM) systems, which is based on an eigenvector decomposition of the estimated Channel Correlation Matrix. Simulation results show that the proposed estimator can obtain accurate real time measurements of the noise variance and SNR after an observation interval of about 20 OFDM symbols for various fading Channels.

Ryuichiro Shimura - One of the best experts on this subject based on the ideXlab platform.

  • transmit phase control to increase the minimum eigenvalue of the Channel Correlation Matrix in the etd system
    Electronics and Communications in Japan Part I-communications, 2007
    Co-Authors: Ryuichiro Shimura, Iwao Sasase
    Abstract:

    For conditions under which the Channel conditions between the transmitting and receiving antennas are known on the transmitter side when TDD (Time Division Duplex) is used in the MIMO (Multi-Input Multi-Output) method, much attention has been devoted to E-SDM (Eigenbeam Space Division Multiplexing), in which the influence of CCI (Co-Channel Interference) is eliminated by making the different transmission signal sequences orthogonal in space by means of the eigenvectors of the Channel Matrix used as the transmission and reception weights. However, in such a system as E-SDM, in which eigenvectors of the Channel Matrix are used, more than two antennas are needed on the receiving side in order to perform eigenvalue decomposition of the Channel Matrix. In this paper, in order to realize a system using the eigenvectors as the transmission and reception weights even in a system with two transmitting antennas and one receiving antenna under TDD, the ETD (Eigenbeam Transmit Diversity) system is proposed. In this system, the concept of frequency diversity is applied, in which identical signals are transmitted on two subcarriers on one transmitting antenna, so that a MIMO system is virtually realized with subcarriers of the OFDM (Orthogonal Frequency Division Multiplexing) in place of receiving antennas in the row direction of the Channel Matrix. In the ETD system, the minimum eigenvalue of the Channel Matrix can be made larger by adaptively interchanging the signals among antennas and by transmission phase control. Hence, the BER characteristics of the signal sequence by which the minimum eigenvalue is multiplied can be improved. The characteristics are evaluated by computer simulations. It is shown that the proposed system is superior in terms of BER characteristics to the transmission diversity system in which transmission phase control is carried out among the antennas. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(7): 38–51, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20342

  • transmit phase control to increase the minimum eigenvalue of Channel Correlation Matrix in the e sdm ofdm system
    Vehicular Technology Conference, 2004
    Co-Authors: Ryuichiro Shimura, T Ohno, T Kambayashi, Iwao Sasase
    Abstract:

    In multiple-input multiple-output (MIMO) systems, the eigen-beam space division multiplexing (E-SDM) system has been proposed for mitigating the effect of co-Channel interference (CCI). Received signal to noise ratio (SNR) in the E-SDM system depends on the eigenvalues of the Channel Correlation Matrix. Consequently, the bit error rate (BER) performance of the data stream multiplied by the minimum eigenvalue is degraded in comparison with that of another data stream. We propose an E-SDM/OFDM system to control the eigenvalues of a Channel Correlation Matrix by using transmit phase control. Computer simulation results indicate the proposed E-SDM/OFDM system with transmit phase control can improve the BER performance compared with E-SDM/OFDM system without using transmit phase control.

Ya Jing - One of the best experts on this subject based on the ideXlab platform.

  • subspace based noise variance and snr estimation for mimo ofdm systems
    Journal of Electronics (china), 2006
    Co-Authors: Xiaodong Xu, Ya Jing, Junhui Zhao, Xiaohu You
    Abstract:

    This paper proposes a subspace-based noise variance and Signal-to-Noise Ratio (SNR) estimation algorithm for Multi-Input Multi-Output (MIMO) wireless Orthogonal Frequency Division Multiplexing (OFDM) systems. The special training sequences with the property of orthogonality and phase shift orthogonality are used in pilot tones to obtain the estimated Channel Correlation Matrix. Partitioning the observation space into a delay subspace and a noise subspace, we achieve the measurement of noise variance and SNR. Simulation results show that the proposed estimator can obtain accurate and real-time measurements of the noise variance and SNR for various multipath fading Channels, demonstrating its strong robustness against different Channels.

  • subspace based noise variance and snr estimation for ofdm systems mobile radio applications
    Wireless Communications and Networking Conference, 2005
    Co-Authors: Xiaodong Xu, Ya Jing, Xiaohu Yu
    Abstract:

    Noise variance and hence signal to noise ratio (SNR) estimates are very important for the Channel quality control in communication systems. Noting that in mobile communications the multipath time delays are slowly varying in time, in this paper we derive a subspace-based estimation method for orthogonal frequency division multiplexing (OFDM) systems, which is based on an eigenvector decomposition of the estimated Channel Correlation Matrix. Simulation results show that the proposed estimator can obtain accurate real time measurements of the noise variance and SNR after an observation interval of about 20 OFDM symbols for various fading Channels.