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Jun Mashinot - One of the best experts on this subject based on the ideXlab platform.

  • undesired signal power estimation based on estimated superposed band for Multicarrier Transmission
    Asia-Pacific Conference on Communications, 2015
    Co-Authors: Yohei Shibata, Tomoaki Ohtsuki, Jun Mashinot
    Abstract:

    Superposed Multicarrier Transmission scheme is known to improve frequency utilization efficiency where several wireless systems share spectrum. On superposed band, log likelihood ratio (LLR) cannot be set correctly due to interference, which results in BER (Bit Error Rate) degradation. Forward error correction (FEC) metric masking is proposed to suppress the effect of interference. In this technique, LLRs corresponding to superposed band is set to zero, because received bits corresponding to superposed band is unreliable. This scheme requires superposed band detection and does not consider channel estimation error. We proposed an iterative estimation technique for undesired signal power in [6]. Although this scheme does not require superposed detection beforehand, due to the estimation error of undesired signal power, BER is degraded. In this paper, we propose an estimation technique for undesired signal power and superposed band to calculate LLR correctly. This scheme estimates the superposed band within 1 packet and based on the information about the superposed band, undesired signal power is estimated using pilot symbols. Simulation results show that as the number of pilot symbols increases, BER of our proposed scheme becomes better than that of [6] and gets closer to the BER when the estimation of undesired signal power is perfect.

  • APCC - Undesired signal power estimation based on estimated superposed band for Multicarrier Transmission
    2015 21st Asia-Pacific Conference on Communications (APCC), 2015
    Co-Authors: Yohei Shibata, Tomoaki Ohtsuki, Jun Mashinot
    Abstract:

    Superposed Multicarrier Transmission scheme is known to improve frequency utilization efficiency where several wireless systems share spectrum. On superposed band, log likelihood ratio (LLR) cannot be set correctly due to interference, which results in BER (Bit Error Rate) degradation. Forward error correction (FEC) metric masking is proposed to suppress the effect of interference. In this technique, LLRs corresponding to superposed band is set to zero, because received bits corresponding to superposed band is unreliable. This scheme requires superposed band detection and does not consider channel estimation error. We proposed an iterative estimation technique for undesired signal power in [6]. Although this scheme does not require superposed detection beforehand, due to the estimation error of undesired signal power, BER is degraded. In this paper, we propose an estimation technique for undesired signal power and superposed band to calculate LLR correctly. This scheme estimates the superposed band within 1 packet and based on the information about the superposed band, undesired signal power is estimated using pilot symbols. Simulation results show that as the number of pilot symbols increases, BER of our proposed scheme becomes better than that of [6] and gets closer to the BER when the estimation of undesired signal power is perfect.

Yohei Shibata - One of the best experts on this subject based on the ideXlab platform.

  • undesired signal power estimation based on estimated superposed band for Multicarrier Transmission
    Asia-Pacific Conference on Communications, 2015
    Co-Authors: Yohei Shibata, Tomoaki Ohtsuki, Jun Mashinot
    Abstract:

    Superposed Multicarrier Transmission scheme is known to improve frequency utilization efficiency where several wireless systems share spectrum. On superposed band, log likelihood ratio (LLR) cannot be set correctly due to interference, which results in BER (Bit Error Rate) degradation. Forward error correction (FEC) metric masking is proposed to suppress the effect of interference. In this technique, LLRs corresponding to superposed band is set to zero, because received bits corresponding to superposed band is unreliable. This scheme requires superposed band detection and does not consider channel estimation error. We proposed an iterative estimation technique for undesired signal power in [6]. Although this scheme does not require superposed detection beforehand, due to the estimation error of undesired signal power, BER is degraded. In this paper, we propose an estimation technique for undesired signal power and superposed band to calculate LLR correctly. This scheme estimates the superposed band within 1 packet and based on the information about the superposed band, undesired signal power is estimated using pilot symbols. Simulation results show that as the number of pilot symbols increases, BER of our proposed scheme becomes better than that of [6] and gets closer to the BER when the estimation of undesired signal power is perfect.

  • iterative estimation of undesired signal power for superposed Multicarrier Transmission with channel estimation error
    Eurasip Journal on Wireless Communications and Networking, 2015
    Co-Authors: Yohei Shibata, Naotoshi Yoda, Tomoaki Ohtsuki, Jun Mashino, Takatoshi Sugiyama
    Abstract:

    Superposed Multicarrier Transmission scheme is known to improve frequency utilization efficiency when several wireless systems share the same spectrum. To suppress the effect of interference, forward error correction (FEC) metric masking is proposed. In this technique, the log-likelihood ratio (LLR) that corresponds to the superposed band is set to zero, because received bits that correspond to the superposed band are unreliable. However, to apply FEC metric masking, the information about superposed band must be known at the receiver beforehand. Furthermore, the received bits contain channel estimation errors, which are the cause of performance degradation. In this paper, we propose an iterative estimation technique for undesired signal power (noise, interference, and channel estimation error) for superposed Multicarrier Transmission. We use the estimated power of the undesired signal to calculate the LLR that takes the channel estimation error into account, since including this extra information about the channel improves the bit error rate (BER). The proposed scheme estimates the power of undesired signal on each subcarrier, and thus, the information about superposed band is not required. Simulation results show that the accuracy of estimating undesired signal becomes more reliable as the number of estimations increases, so that BER becomes better as a result of iterative estimation.

  • APCC - Undesired signal power estimation based on estimated superposed band for Multicarrier Transmission
    2015 21st Asia-Pacific Conference on Communications (APCC), 2015
    Co-Authors: Yohei Shibata, Tomoaki Ohtsuki, Jun Mashinot
    Abstract:

    Superposed Multicarrier Transmission scheme is known to improve frequency utilization efficiency where several wireless systems share spectrum. On superposed band, log likelihood ratio (LLR) cannot be set correctly due to interference, which results in BER (Bit Error Rate) degradation. Forward error correction (FEC) metric masking is proposed to suppress the effect of interference. In this technique, LLRs corresponding to superposed band is set to zero, because received bits corresponding to superposed band is unreliable. This scheme requires superposed band detection and does not consider channel estimation error. We proposed an iterative estimation technique for undesired signal power in [6]. Although this scheme does not require superposed detection beforehand, due to the estimation error of undesired signal power, BER is degraded. In this paper, we propose an estimation technique for undesired signal power and superposed band to calculate LLR correctly. This scheme estimates the superposed band within 1 packet and based on the information about the superposed band, undesired signal power is estimated using pilot symbols. Simulation results show that as the number of pilot symbols increases, BER of our proposed scheme becomes better than that of [6] and gets closer to the BER when the estimation of undesired signal power is perfect.

  • iterative estimation of undesired signal power for superposed Multicarrier Transmission with channel estimation error
    Personal Indoor and Mobile Radio Communications, 2014
    Co-Authors: Yohei Shibata, Naotoshi Yoda, Tomoaki Ohtsuki, Jun Mashino, Takatoshi Sugiyama
    Abstract:

    Superposed Multicarrier Transmission scheme is known to improve frequency utilization efficiency when several wireless systems share the same spectrum. To suppress the effect of interference, forward error correction (FEC) metric masking is proposed. In the technique, log-likelihood ratio (LLR) that corresponds to superposed band is set to zero, because received bits that correspond to superposed band is unreliable. However, to apply FEC metric masking, the information about superposed band must be known at the receiver beforehand. Furthermore, the received bits contain channel estimation error, which is a cause of degradation. In this paper, we propose an iterative estimation technique of power of undesired signal (noise, interference, and channel estimation error) for superposed Multicarrier Transmission. We use the estimated power of the undesired signal to calculate the LLR that takes the channel estimation error into account, since including this extra information about the channel improves the BER. The proposed scheme estimates the power of undesired signal on each subcarrier, thus the information about superposed band is not required. Simulation results show that the accuracy of estimating undesired signal becomes more reliable as the number of estimation increases, so that BER becomes better as a result of iterative estimation.

  • PIMRC - Iterative estimation of undesired signal power for superposed Multicarrier Transmission with channel estimation error
    2014 IEEE 25th Annual International Symposium on Personal Indoor and Mobile Radio Communication (PIMRC), 2014
    Co-Authors: Yohei Shibata, Naotoshi Yoda, Tomoaki Ohtsuki, Jun Mashino, Takatoshi Sugiyama
    Abstract:

    Superposed Multicarrier Transmission scheme is known to improve frequency utilization efficiency when several wireless systems share the same spectrum. To suppress the effect of interference, forward error correction (FEC) metric masking is proposed. In the technique, log-likelihood ratio (LLR) that corresponds to superposed band is set to zero, because received bits that correspond to superposed band is unreliable. However, to apply FEC metric masking, the information about superposed band must be known at the receiver beforehand. Furthermore, the received bits contain channel estimation error, which is a cause of degradation. In this paper, we propose an iterative estimation technique of power of undesired signal (noise, interference, and channel estimation error) for superposed Multicarrier Transmission. We use the estimated power of the undesired signal to calculate the LLR that takes the channel estimation error into account, since including this extra information about the channel improves the BER. The proposed scheme estimates the power of undesired signal on each subcarrier, thus the information about superposed band is not required. Simulation results show that the accuracy of estimating undesired signal becomes more reliable as the number of estimation increases, so that BER becomes better as a result of iterative estimation.

Dongmei Zhang - One of the best experts on this subject based on the ideXlab platform.

  • VTC Spring - Integer Frequency Offset Estimation for Dynamic Lattice Multicarrier Transmission System over Time-Varying Rayleigh Fading Channel
    2016 IEEE 83rd Vehicular Technology Conference (VTC Spring), 2016
    Co-Authors: Wei Xie, Dongmei Zhang
    Abstract:

    In this paper, we study the integer carrier frequency offset (ICFO) estimation problem for dynamic lattice Multicarrier Transmission (DLMT) system over time-varying rayleigh fading channel. Firstly, a novel preamble structure based on two constant amplitude zero auto-correlation (CAZAC) sequences is designed for DLMT system. The proposed preamble structure is named as dual-CAZAC preamble. Then, by using the designed dual-CAZAC preamble, a weighted cross ambiguity function (WCAF) based ICFO estimation algorithm is proposed. Simulation results show that the proposed WCAF based ICFO estimation algorithm can mitigate the impact of time-varying multipath rayleigh fading channel and outperforms traditional ICFO estimator on the correct estimation probability performance.

  • ChinaCom - On adaptive reception for Dynamic Lattice Multicarrier Transmission system with varying speed receiver
    2015 10th International Conference on Communications and Networking in China (ChinaCom), 2015
    Co-Authors: Dongmei Zhang
    Abstract:

    In this paper, an adaptive reception scheme for Dynamic Lattice Multicarrier Transmission (DLMT) system with varying speed receiver is proposed. Theoretical analyses show that there is a timing offset between the prototype pulses of the proposed adaptive receiver and the traditional projection receiver. Meanwhile, the timing offset and prototype pulse should be adapted to the non-stationary doubly dispersive (NSDD) channel introduced by the user mobility. The closed-form timing offset expression of the proposed adaptive receiver over NSDD channel is derived. Simulation results show that the prototype pulse of the proposed adaptive receiver matches the user mobility with a greater dynamic range when compared with the iterative receiver and the Max-SINR receiver designed for stationary wireless channel. Meanwhile, the Signal-to-Interference-plus-Noise Ratio (SINR) performance of the proposed adaptive receiver outperforms traditional projection receiver, iterative receiver and the Max-SINR receiver.

  • Time and Frequency Synchronization for Multicarrier Transmission on Hexagonal Time-Frequency Lattice
    IEEE Transactions on Signal Processing, 2013
    Co-Authors: Wei Xie, Dongmei Zhang
    Abstract:

    In this paper, a novel synchronization acquisition approach, including preamble structure, time and frequency synchronization algorithms, is proposed for hexagonal Multicarrier Transmission (HMCT) system. Specifically, a novel signal acquisition scheme based on time-frequency subspace projection (TFSP) and its simplified form are proposed for reliable signal acquisition. Time and frequency synchronization is divided into three steps: 1) the coarse time offset (TO) and coarse fractional carrier frequency offset (CFO) estimation; 2) fine TO and integer CFO estimation; and 3) fine fractional CFO estimation. The closed-form Cramer-Rao lower bound of the proposed CFO estimation scheme is given. Theoretical analyses and simulation results show that the proposed preamble structure, time and frequency synchronization algorithms for HMCT system can obtain robust performance over doubly dispersive (DD) channel, and the simulation results show excellent agreement with theoretical analyses.

  • Max-SINR Based Timing Synchronization Scheme in Hexagonal Multicarrier Transmission
    Wireless Personal Communications, 2012
    Co-Authors: Dongmei Zhang, Xinyi Zhong, Wenwen Liang
    Abstract:

    In this paper, the maximizing Signal-to-Interference-plus-Noise Ratio (Max-SINR) criterion is applied in Hexagonal Multicarrier Transmission (HMT) system for timing synchronization. An iterative approach for Max-SINR timing over doubly dispersive (DD) channel with exponential power delay profile and U-shape Doppler spectrum is proposed. Theoretical analysis shows that there is an allowable SINR gap between the mean delay of DD channel and the optimal timing point. Meanwhile, a low complexity suboptimal timing approach based on instantaneous channel frequency response is proposed. Theoretical analysis and simulation results show that Max-SINR timing scheme outperforms traditional timing method about 2–15 dB in SINR and the suboptimal timing algorithm achieves a smaller Mean Square Error than 10−4 over DD channels. In addition, the Iterative Projection Sequence Detection (IPSD) receiver is proposed and the Match Filter Low Bound (MFLB) in HMT system is given. Simulation results show that the Bit Error Rate (BER) of the proposed IPSD approach based on iterative Max-SINR timing approximates to the MFLB and outperforms traditional timing scheme about 3dB at BER = 10−3.

  • On Max-SINR Receiver for Hexagonal Multicarrier Transmission Over Doubly Dispersive Channel
    2012 IEEE Global Communications Conference (GLOBECOM), 2012
    Co-Authors: Xiaochen Xia, Dongmei Zhang
    Abstract:

    In this paper, a novel receiver for Hexagonal Multicarrier Transmission (HMT) system based on the maximizing Signal-to-Interference-plus-Noise Ratio (Max-SINR) criterion is proposed. Theoretical analysis shows that the prototype pulse of the proposed Max-SINR receiver should adapt to the root mean square (RMS) delay spread of the doubly dispersive (DD) channel with exponential power delay profile and U-shape Doppler spectrum. Simulation results show that the proposed Max-SINR receiver outperforms traditional projection scheme and obtains an approximation to the theoretical upper bound SINR performance within the full range of channel spread factor. Meanwhile, the SINR performance of the proposed prototype pulse is robust to the estimation error between the estimated value and the real value of time delay spread.

Xian-da Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Asymptotic Equivalence of Two Multicarrier Transmission Schemes in Terms of Robustness Against Time–Frequency Dispersive Channels
    IEEE Transactions on Vehicular Technology, 2010
    Co-Authors: Fang-ming Han, Xian-da Zhang
    Abstract:

    Digital signal Transmission can be viewed as lattice-tiling over a time-frequency plane. Corresponding to a rectangular lattice and a hexagonal lattice, there are two Multicarrier Transmission schemes, i.e., the Weyl-Heisenberg (W-H) system and the hexagonal Gabor (H-G) system, respectively. In the previous works, the Transmission pulse shape and the time-frequency lattice parameters of the above two systems were optimized to obtain the best robustness against time-frequency dispersive channels. In this paper, by virtue of elliptic integral theory, we theoretically prove that the optimized W-H system and H-G system are asymptotically equivalent to each other in the sense of achieving the same energy perturbation as signaling efficiency approaches 0 or +?. Moreover, it is shown that, for moderate signaling efficiencies, the superiority of the H-G system over the W-H system is virtually limited. Numerical results are provided to support the theoretical analysis.

  • MLSD for Hexagonal Multicarrier Transmission With Time–Frequency Localized Pulses
    IEEE Transactions on Vehicular Technology, 2009
    Co-Authors: Fang-ming Han, Xian-da Zhang
    Abstract:

    Due to the well-separated lattice structure, the excellent time-frequency (T-F) concentration of the modulation pulses, and the under spread property of the mobile radio channels, the pulse cross-correlation matrix (PCCM) at the receiver in a properly designed hexagonal Multicarrier Transmission scheme essentially takes on a band-limited and sparse structure. By neglecting the almost-zero-valued entries in the PCCM and rearranging the data vector with the aid of the pilot symbols, we propose a parallel maximum-likelihood sequence detection (MLSD), which decomposes the original large-sized MLSD into several small-sized MLSDs that independently operate. With the parallel MLSD via the dynamic programming algorithm, the global maximization of the log likelihood is guaranteed. The signal-to-noise ratio (SNR) loss due to such idealization of the PCCM is analytically evaluated. It is shown that, when the signaling efficiency, i.e., a quantity characterizing the density of symbols in the T-F plane, is not so large, the performance degradation is negligible, compared with that caused by the background noise in practical environment. Simulation results are presented to confirm the effectiveness of the proposed parallel MLSD scheme.

  • hexagonal Multicarrier modulation a robust Transmission scheme for time frequency dispersive channels
    IEEE Transactions on Signal Processing, 2007
    Co-Authors: Fang-ming Han, Xian-da Zhang
    Abstract:

    By regarding signal Transmission as tiling of the time-frequency plane, we propose a Multicarrier Transmission scheme on hexagonal lattice, coined the term hexagonal Multicarrier modulation. To optimally combat the impact of the propagation channels, the underlying lattice parameters and the pulse shape of modulation waveform are jointly optimized to adapt to the channel scattering function from a minimum energy perturbation point of view. It comes out that there exist two equivalent pulse and lattice matching criteria for each channel scattering function to achieve minimal interpulse interference (IPI). Robustness of the proposed system against the wireless channels is analyzed in terms of robustness factor. Numerical analysis and simulation results show that the hexagonal Multicarrier Transmission system outperforms conventional orthogonal-frequency-division multiplexing (OFDM) and lattice-OFDM (LOFDM) systems with regard to robustness against channel dispersion

Tomoaki Ohtsuki - One of the best experts on this subject based on the ideXlab platform.

  • suppression of multiple interferences for superposed Multicarrier Transmission
    Personal Indoor and Mobile Radio Communications, 2015
    Co-Authors: Yuto Kakizaki, Tomoaki Ohtsuki, Jun Mashino
    Abstract:

    Superposed Multicarrier Transmission is proposed as one of the schemes that improve frequency utilization efficiency. In this scheme some wireless systems share the same spectrum, and interference suppression is necessary. One conventional scheme for the interference suppression applies the EM (Expectation Maximization) algorithm for the estimation of interference parameters, and another scheme iterates the estimation of the parameters based on undesired signal power. However, these schemes assume the same average power for all interferences, which makes accuracy of the estimated power decrease and results in degradation of BER (Bit Error Rate) when the average power of each interference is not same. In this paper, we propose a suppression schemes for multiple interferences with different average power levels. In our scheme, undesired signal power is averaged in both the time and the frequency domain, after which it is compared to threshold to determine if the corresponding subcarrier is superposed or not. According to the result of this comparison, the power of each interference is estimated. Furthermore, the threshold is iteratively recalculated when the estimated parameters are updated. Through simulations we show that the proposed scheme taking the different average power of interference into account shows better BER performance than that of conventional ones assuming the same average power of interference. In addition, we show that averaging undesired signal power in both the time and the frequency domain and iterative calculation of threshold lead to improvement of the accuracy of superposed band detection.

  • undesired signal power estimation based on estimated superposed band for Multicarrier Transmission
    Asia-Pacific Conference on Communications, 2015
    Co-Authors: Yohei Shibata, Tomoaki Ohtsuki, Jun Mashinot
    Abstract:

    Superposed Multicarrier Transmission scheme is known to improve frequency utilization efficiency where several wireless systems share spectrum. On superposed band, log likelihood ratio (LLR) cannot be set correctly due to interference, which results in BER (Bit Error Rate) degradation. Forward error correction (FEC) metric masking is proposed to suppress the effect of interference. In this technique, LLRs corresponding to superposed band is set to zero, because received bits corresponding to superposed band is unreliable. This scheme requires superposed band detection and does not consider channel estimation error. We proposed an iterative estimation technique for undesired signal power in [6]. Although this scheme does not require superposed detection beforehand, due to the estimation error of undesired signal power, BER is degraded. In this paper, we propose an estimation technique for undesired signal power and superposed band to calculate LLR correctly. This scheme estimates the superposed band within 1 packet and based on the information about the superposed band, undesired signal power is estimated using pilot symbols. Simulation results show that as the number of pilot symbols increases, BER of our proposed scheme becomes better than that of [6] and gets closer to the BER when the estimation of undesired signal power is perfect.

  • iterative estimation of undesired signal power for superposed Multicarrier Transmission with channel estimation error
    Eurasip Journal on Wireless Communications and Networking, 2015
    Co-Authors: Yohei Shibata, Naotoshi Yoda, Tomoaki Ohtsuki, Jun Mashino, Takatoshi Sugiyama
    Abstract:

    Superposed Multicarrier Transmission scheme is known to improve frequency utilization efficiency when several wireless systems share the same spectrum. To suppress the effect of interference, forward error correction (FEC) metric masking is proposed. In this technique, the log-likelihood ratio (LLR) that corresponds to the superposed band is set to zero, because received bits that correspond to the superposed band are unreliable. However, to apply FEC metric masking, the information about superposed band must be known at the receiver beforehand. Furthermore, the received bits contain channel estimation errors, which are the cause of performance degradation. In this paper, we propose an iterative estimation technique for undesired signal power (noise, interference, and channel estimation error) for superposed Multicarrier Transmission. We use the estimated power of the undesired signal to calculate the LLR that takes the channel estimation error into account, since including this extra information about the channel improves the bit error rate (BER). The proposed scheme estimates the power of undesired signal on each subcarrier, and thus, the information about superposed band is not required. Simulation results show that the accuracy of estimating undesired signal becomes more reliable as the number of estimations increases, so that BER becomes better as a result of iterative estimation.

  • PIMRC - Suppression of multiple interferences for superposed Multicarrier Transmission
    2015 IEEE 26th Annual International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC), 2015
    Co-Authors: Yuto Kakizaki, Tomoaki Ohtsuki, Jun Mashino
    Abstract:

    Superposed Multicarrier Transmission is proposed as one of the schemes that improve frequency utilization efficiency. In this scheme some wireless systems share the same spectrum, and interference suppression is necessary. One conventional scheme for the interference suppression applies the EM (Expectation Maximization) algorithm for the estimation of interference parameters, and another scheme iterates the estimation of the parameters based on undesired signal power. However, these schemes assume the same average power for all interferences, which makes accuracy of the estimated power decrease and results in degradation of BER (Bit Error Rate) when the average power of each interference is not same. In this paper, we propose a suppression schemes for multiple interferences with different average power levels. In our scheme, undesired signal power is averaged in both the time and the frequency domain, after which it is compared to threshold to determine if the corresponding subcarrier is superposed or not. According to the result of this comparison, the power of each interference is estimated. Furthermore, the threshold is iteratively recalculated when the estimated parameters are updated. Through simulations we show that the proposed scheme taking the different average power of interference into account shows better BER performance than that of conventional ones assuming the same average power of interference. In addition, we show that averaging undesired signal power in both the time and the frequency domain and iterative calculation of threshold lead to improvement of the accuracy of superposed band detection.

  • APCC - Undesired signal power estimation based on estimated superposed band for Multicarrier Transmission
    2015 21st Asia-Pacific Conference on Communications (APCC), 2015
    Co-Authors: Yohei Shibata, Tomoaki Ohtsuki, Jun Mashinot
    Abstract:

    Superposed Multicarrier Transmission scheme is known to improve frequency utilization efficiency where several wireless systems share spectrum. On superposed band, log likelihood ratio (LLR) cannot be set correctly due to interference, which results in BER (Bit Error Rate) degradation. Forward error correction (FEC) metric masking is proposed to suppress the effect of interference. In this technique, LLRs corresponding to superposed band is set to zero, because received bits corresponding to superposed band is unreliable. This scheme requires superposed band detection and does not consider channel estimation error. We proposed an iterative estimation technique for undesired signal power in [6]. Although this scheme does not require superposed detection beforehand, due to the estimation error of undesired signal power, BER is degraded. In this paper, we propose an estimation technique for undesired signal power and superposed band to calculate LLR correctly. This scheme estimates the superposed band within 1 packet and based on the information about the superposed band, undesired signal power is estimated using pilot symbols. Simulation results show that as the number of pilot symbols increases, BER of our proposed scheme becomes better than that of [6] and gets closer to the BER when the estimation of undesired signal power is perfect.