The Experts below are selected from a list of 642 Experts worldwide ranked by ideXlab platform
Zhengyuan Xu - One of the best experts on this subject based on the ideXlab platform.
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Correlation-Based LTI Channel Estimation for Multi-Wavelength Optical Scattering NLOS Communication
IEEE Transactions on Communications, 2020Co-Authors: Chen Gong, Julian Cheng, Zhengyuan XuAbstract:Strong correlation of link gains over multiple wavelengths has been demonstrated in non-line-of-sight optical wireless scattering communication. In this paper, we further demonstrate the strong correlation of the Channel impulse responses for different wavelengths. A novel Channel estimation method is proposed based on such correlation, where only certain reference wavelengths are assigned with pilot signals. On each Channel assigned by the pilot signal, we adopt an improved least-squares method to estimate the Channel Tap coefficients and the Tap length. The Channel Tap coefficients for other wavelengths can be estimated based on the inter-wavelength correlation. Under the proposed Channel estimation, the Channel estimation accuracy can be improved as shown by the simulations. We further propose an optimization method for the correlation-based Channel estimation pilot pattern based on the receiver Channel state feedback. Simulation results show that optimized pilot pattern can achieve significant performance gain over the fixed pilot pattern. Moreover, the Channel estimation performance is insensitive to the Channel state feedback frequency.
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Correlation-Based LTI Channel Estimation for Multi-Wavelength Optical Scattering Communication
ICC 2019 - 2019 IEEE International Conference on Communications (ICC), 2019Co-Authors: Chen Gong, Julian Cheng, Zhengyuan XuAbstract:Strong correlation of link gains over multiple wavelengths has been demonstrated in non-line-of-sight optical wireless scattering communication. In this paper, we further demonstrate that the Channel impulse responses for different wavelengths are also strongly correlated. Thus, a novel Channel estimation method based on such correlation over multiple wavelengths is proposed, where only certain reference wavelengths are assigned pilot signal. On each Channel with assigned pilot signal, we adopt an improved least-squares Channel estimation method to estimate the Tap parameters and the Tap length (or the number of Taps). The Channel Tap coefficients on other wavelengths can be estimated based on the correlation. Under the proposed Channel estimation, the Channel estimation accuracy can be improved as shown by the simulations. Moreover, under the same total Channel estimation overhead, the accuracy of the proposed Channel estimation first increases and then decreases with the number of reference wavelengths.
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ICC - Correlation-Based LTI Channel Estimation for Multi-Wavelength Optical Scattering Communication
ICC 2019 - 2019 IEEE International Conference on Communications (ICC), 2019Co-Authors: Chen Gong, Julian Cheng, Zhengyuan XuAbstract:Strong correlation of link gains over multiple wavelengths has been demonstrated in non-line-of-sight optical wireless scattering communication. In this paper, we further demonstrate that the Channel impulse responses for different wavelengths are also strongly correlated. Thus, a novel Channel estimation method based on such correlation over multiple wavelengths is proposed, where only certain reference wavelengths are assigned pilot signal. On each Channel with assigned pilot signal, we adopt an improved least-squares Channel estimation method to estimate the Tap parameters and the Tap length (or the number of Taps). The Channel Tap coefficients on other wavelengths can be estimated based on the correlation. Under the proposed Channel estimation, the Channel estimation accuracy can be improved as shown by the simulations. Moreover, under the same total Channel estimation overhead, the accuracy of the proposed Channel estimation first increases and then decreases with the number of reference wavelengths.
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Optical wireless scattering Channel estimation for photon-counting receiver
2016 IEEE International Conference on Communications (ICC), 2016Co-Authors: Chen Gong, Zhengyuan Xu, Xiaoke Zhang, Lajos HanzoAbstract:Channel estimation is conceived for optical wireless scattering Channels associated with Laser Diode transmitters and photon-counting/photomultiplier tube receivers. The proposed Channel estimation approach consists of two stages, namely the estimation of the Channel Tap second-order moments followed by the estimation of the Channel Taps based on the estimate of second-order moments. In the first stage, we provide the general framework of the moment estimation complemented by the conception of an estimation approach based on a sparse pilot structure, as well as by the analysis of the estimation error. In the second stage, we conceive the Channel Tap estimation based on the eigenvalue decomposition of the matrix of estimated second-order moments, and analyze the associated performance. It is shown that as the length of the pilot sequence approaches infinity, the probability of having an estimation distortion above a threshold can be arbitrarily small. Simulation results show that a sparse pilot sequence can lead to a smaller estimation error than its counterpart using random 0-1 bits.
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ICC - Optical wireless scattering Channel estimation for photon-counting receiver
2016 IEEE International Conference on Communications (ICC), 2016Co-Authors: Chen Gong, Zhengyuan Xu, Xiaoke Zhang, Lajos HanzoAbstract:Channel estimation is conceived for optical wireless scattering Channels associated with Laser Diode transmitters and photon-counting/photomultiplier tube receivers. The proposed Channel estimation approach consists of two stages, namely the estimation of the Channel Tap second-order moments followed by the estimation of the Channel Taps based on the estimate of second-order moments. In the first stage, we provide the general framework of the moment estimation complemented by the conception of an estimation approach based on a sparse pilot structure, as well as by the analysis of the estimation error. In the second stage, we conceive the Channel Tap estimation based on the eigenvalue decomposition of the matrix of estimated second-order moments, and analyze the associated performance. It is shown that as the length of the pilot sequence approaches infinity, the probability of having an estimation distortion above a threshold can be arbitrarily small. Simulation results show that a sparse pilot sequence can lead to a smaller estimation error than its counterpart using random 0–1 bits.
Wen-long Chin - One of the best experts on this subject based on the ideXlab platform.
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ICNC - Non-cooperative and cooperative PUEA detection using physical layer in mobile OFDM-based cognitive radio networks
2016 International Conference on Computing Networking and Communications (ICNC), 2016Co-Authors: Trong Nghia Le, Wen-long ChinAbstract:This work proposes novel non-cooperative and cooperative detection methods for identifying primary user emulation attacks (PUEAs) based on a Channel-Tap power in mobile OFDM-based CR networks. The Channel-Tap power is utilized as a radio-frequency fingerprint (RFF) to directly detect users via physical (PHY) layer. A Channel-based detection for the noncooperative detection is proposed using the Neyman-Pearson test to discriminate between the primary users (PUs) and PUEAs. To improve the detection performance in the shadowing and fading environment, the cooperative detection scheme using the fixed sample size test (FSST) is devised. The proposed methods helps PHY layer completely detect the identities of PUs and PUEAs. From simulation results, for a mobile CR speed of 70 km/h, SNR=−5 dB, and false alarm probability of 0.03, the FSST using ten cooperative nodes can achieve the detection probability of 0.99, which is increased by 1.94 times that of a single node.
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Non-cooperative and cooperative PUEA detection using physical layer in mobile OFDM-based cognitive radio networks
2016 International Conference on Computing, Networking and Communications (ICNC), 2016Co-Authors: Trong Nghia Le, Wen-long Chin, Ya-Hsuan LinAbstract:This work proposes novel non-cooperative and cooperative detection methods for identifying primary user emulation attacks (PUEAs) based on a Channel-Tap power in mobile OFDM-based CR networks. The Channel-Tap power is utilized as a radio-frequency fingerprint (RFF) to directly detect users via physical (PHY) layer. A Channel-based detection for the noncooperative detection is proposed using the Neyman-Pearson test to discriminate between the primary users (PUs) and PUEAs. To improve the detection performance in the shadowing and fading environment, the cooperative detection scheme using the fixed sample size test (FSST) is devised. The proposed methods helps PHY layer completely detect the identities of PUs and PUEAs. From simulation results, for a mobile CR speed of 70 km/h, SNR=-5 dB, and false alarm probability of 0.03, the FSST using ten cooperative nodes can achieve the detection probability of 0.99, which is increased by 1.94 times that of a single node.
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Cross-Layer Design for Primary User Emulation Attacks Detection in Mobile Cognitive Radio Networks
IEEE Communications Letters, 2015Co-Authors: Trong Nghia Le, Wen-long Chin, Wei-Che KaoAbstract:In this letter, the Channel-Tap power is utilized as a radio-frequency fingerprint (RF) to completely identify primary user emulation attacks (PUEAs) over multipath Rayleigh fading Channels. To accurately know identities of primary users (PUs) and PUEAs, the cross-layer intelligent learning ability of a mobile secondary user (SU) is exploited to establish detection databases by seamlessly combining the quick detection of physical (PHY) layer with the accuracy of higher layer authentication. The proposed method helps PHY layer completely detect the identities of PUs and PUEAs. For SNR = -2 dB and the false alarm probability of 0.1, the SU can detect a PUEA with the detection probability of 0.9673 under the mobile speed of 70 km/h.
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cooperative detection of primary user emulation attacks based on Channel Tap power in mobile cognitive radio networks
Ubiquitous Computing, 2014Co-Authors: Wen-long Chin, Trong Nghia Le, Chunlin Tseng, Chunshen TsaiAbstract:This work proposes a new method for identifying a primary user emulation attack PUEA at low signal-to-noise ratios SNRs in mobile cognitive radio CR networks. Channel-Tap power is utilised as a radio-frequency RF fingerprint to directly detect users via physical PHY layer. To improve the detection performance in fading Channels, the cooperative detection schemes using the fixed sample size test FSST and the sequential probability ratio test SPRT are devised. From simulation results, for a mobile CR speed of 70 km/h, SNR = -5 dB and false alarm probability of 0.03, the FSST using 10 cooperative nodes can achieve the detection probability of 0.99, which is increased by 1.94 times that of the single Neyman-Pearson detector. When the SPRT is compared to the FSST, the SPRT only needs less than half of the detection time of the FSST to provide the same detection performance for all SNRs considered.
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Blind Symbol Synchronization for OFDM Systems Using Cyclic Prefix in Time-Variant and Long-Echo Fading Channels
IEEE Transactions on Vehicular Technology, 2012Co-Authors: Wen-long ChinAbstract:In this paper, blind symbol synchronization for orthogonal frequency-division multiplexing (OFDM) systems based on the cyclic prefix (CP), considering time-variant long-echo fading Channels, is introduced. The basic idea of our contribution is to obtain an estimate of Channel-Tap powers using the correlation characteristics of the CP. The maximum-likelihood (ML) estimation of the correlation characteristics is derived and employed for Channel-Tap power estimation. An intersymbol-interference (ISI) metric is minimized using the estimate of Channel-Tap powers. The metric, which is based on the statistical properties of received samples, turns the mobility factor into a coefficient, which can be simply compensated. The metric is suitable for both short- and long-echo Channels. The performance is analyzed. The proposed algorithm has moderate complexity. Simulations confirm the advantages of the proposed estimator.
Chen Gong - One of the best experts on this subject based on the ideXlab platform.
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Correlation-Based LTI Channel Estimation for Multi-Wavelength Optical Scattering NLOS Communication
IEEE Transactions on Communications, 2020Co-Authors: Chen Gong, Julian Cheng, Zhengyuan XuAbstract:Strong correlation of link gains over multiple wavelengths has been demonstrated in non-line-of-sight optical wireless scattering communication. In this paper, we further demonstrate the strong correlation of the Channel impulse responses for different wavelengths. A novel Channel estimation method is proposed based on such correlation, where only certain reference wavelengths are assigned with pilot signals. On each Channel assigned by the pilot signal, we adopt an improved least-squares method to estimate the Channel Tap coefficients and the Tap length. The Channel Tap coefficients for other wavelengths can be estimated based on the inter-wavelength correlation. Under the proposed Channel estimation, the Channel estimation accuracy can be improved as shown by the simulations. We further propose an optimization method for the correlation-based Channel estimation pilot pattern based on the receiver Channel state feedback. Simulation results show that optimized pilot pattern can achieve significant performance gain over the fixed pilot pattern. Moreover, the Channel estimation performance is insensitive to the Channel state feedback frequency.
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Correlation-Based LTI Channel Estimation for Multi-Wavelength Optical Scattering Communication
ICC 2019 - 2019 IEEE International Conference on Communications (ICC), 2019Co-Authors: Chen Gong, Julian Cheng, Zhengyuan XuAbstract:Strong correlation of link gains over multiple wavelengths has been demonstrated in non-line-of-sight optical wireless scattering communication. In this paper, we further demonstrate that the Channel impulse responses for different wavelengths are also strongly correlated. Thus, a novel Channel estimation method based on such correlation over multiple wavelengths is proposed, where only certain reference wavelengths are assigned pilot signal. On each Channel with assigned pilot signal, we adopt an improved least-squares Channel estimation method to estimate the Tap parameters and the Tap length (or the number of Taps). The Channel Tap coefficients on other wavelengths can be estimated based on the correlation. Under the proposed Channel estimation, the Channel estimation accuracy can be improved as shown by the simulations. Moreover, under the same total Channel estimation overhead, the accuracy of the proposed Channel estimation first increases and then decreases with the number of reference wavelengths.
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ICC - Correlation-Based LTI Channel Estimation for Multi-Wavelength Optical Scattering Communication
ICC 2019 - 2019 IEEE International Conference on Communications (ICC), 2019Co-Authors: Chen Gong, Julian Cheng, Zhengyuan XuAbstract:Strong correlation of link gains over multiple wavelengths has been demonstrated in non-line-of-sight optical wireless scattering communication. In this paper, we further demonstrate that the Channel impulse responses for different wavelengths are also strongly correlated. Thus, a novel Channel estimation method based on such correlation over multiple wavelengths is proposed, where only certain reference wavelengths are assigned pilot signal. On each Channel with assigned pilot signal, we adopt an improved least-squares Channel estimation method to estimate the Tap parameters and the Tap length (or the number of Taps). The Channel Tap coefficients on other wavelengths can be estimated based on the correlation. Under the proposed Channel estimation, the Channel estimation accuracy can be improved as shown by the simulations. Moreover, under the same total Channel estimation overhead, the accuracy of the proposed Channel estimation first increases and then decreases with the number of reference wavelengths.
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Optical wireless scattering Channel estimation for photon-counting receiver
2016 IEEE International Conference on Communications (ICC), 2016Co-Authors: Chen Gong, Zhengyuan Xu, Xiaoke Zhang, Lajos HanzoAbstract:Channel estimation is conceived for optical wireless scattering Channels associated with Laser Diode transmitters and photon-counting/photomultiplier tube receivers. The proposed Channel estimation approach consists of two stages, namely the estimation of the Channel Tap second-order moments followed by the estimation of the Channel Taps based on the estimate of second-order moments. In the first stage, we provide the general framework of the moment estimation complemented by the conception of an estimation approach based on a sparse pilot structure, as well as by the analysis of the estimation error. In the second stage, we conceive the Channel Tap estimation based on the eigenvalue decomposition of the matrix of estimated second-order moments, and analyze the associated performance. It is shown that as the length of the pilot sequence approaches infinity, the probability of having an estimation distortion above a threshold can be arbitrarily small. Simulation results show that a sparse pilot sequence can lead to a smaller estimation error than its counterpart using random 0-1 bits.
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ICC - Optical wireless scattering Channel estimation for photon-counting receiver
2016 IEEE International Conference on Communications (ICC), 2016Co-Authors: Chen Gong, Zhengyuan Xu, Xiaoke Zhang, Lajos HanzoAbstract:Channel estimation is conceived for optical wireless scattering Channels associated with Laser Diode transmitters and photon-counting/photomultiplier tube receivers. The proposed Channel estimation approach consists of two stages, namely the estimation of the Channel Tap second-order moments followed by the estimation of the Channel Taps based on the estimate of second-order moments. In the first stage, we provide the general framework of the moment estimation complemented by the conception of an estimation approach based on a sparse pilot structure, as well as by the analysis of the estimation error. In the second stage, we conceive the Channel Tap estimation based on the eigenvalue decomposition of the matrix of estimated second-order moments, and analyze the associated performance. It is shown that as the length of the pilot sequence approaches infinity, the probability of having an estimation distortion above a threshold can be arbitrarily small. Simulation results show that a sparse pilot sequence can lead to a smaller estimation error than its counterpart using random 0–1 bits.
Wenhui Xiong - One of the best experts on this subject based on the ideXlab platform.
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the 5 ghz airport surface area Channel part ii measurement and modeling results for small airports
IEEE Transactions on Vehicular Technology, 2008Co-Authors: David W Matolak, Wenhui XiongAbstract:We describe results from a Channel measurement and modeling campaign for the airport surface environment in the 5-GHz band. Using a 50-MHz bandwidth test signal, thousands of power delay profiles (PDPs) were obtained and processed to develop empirical Tapped-delay line statistical Channel models for large airports. A log-distance path loss model was also developed. The large airport surface Channel is classified into three propagation regions, and models are presented for each of the regions for two values of bandwidth. Values of the median root-mean-square (RMS) delay spread range from 500 to 1000 ns for these airports, with the 90 th percentile RMS delay spreads being approximately 1.7 ms. Corresponding correlation bandwidths (i.e., correlation value 1/2) range from approximately 1.5 MHz in non-line-of-sight (NLOS) settings to 17.5 MHz in line-of-sight (LOS) settings. Two types of statistical nonstationarity were also observed: 1) multipath component persistence and 2) propagation region transitions. We provide the multipath component probability of occurrence models and describe Markov chains that are used for modeling both phenomena. Channel Tap amplitude statistics are also provided, using the flexible Weibull probability density function (pdf). This pdf was found to best fit fading Tap amplitude data, particularly for frequently observed severe fading, which is characterized by fade probabilities that are worse than the commonly used Rayleigh model. Fading parameters equivalent to Nakagami-m-model values of m near 0.7 were often observed (with m = 1 being Rayleigh and m < 1 being worse than Rayleigh). We also provide Channel Tap amplitude correlation coefficients, which typically range from 0.1 to 0.4 but occasionally take values greater than 0.7.
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The 5-GHz Airport Surface Area Channel—Part II: Measurement and Modeling Results for Small Airports
IEEE Transactions on Vehicular Technology, 2008Co-Authors: David W Matolak, Wenhui XiongAbstract:We describe results from a Channel measurement and modeling campaign for the airport surface environment in the 5-GHz band. Using a 50-MHz bandwidth test signal, thousands of power delay profiles (PDPs) were obtained and processed to develop empirical Tapped-delay line statistical Channel models for large airports. A log-distance path loss model was also developed. The large airport surface Channel is classified into three propagation regions, and models are presented for each of the regions for two values of bandwidth. Values of the median root-mean-square (RMS) delay spread range from 500 to 1000 ns for these airports, with the 90 th percentile RMS delay spreads being approximately 1.7 ms. Corresponding correlation bandwidths (i.e., correlation value 1/2) range from approximately 1.5 MHz in non-line-of-sight (NLOS) settings to 17.5 MHz in line-of-sight (LOS) settings. Two types of statistical nonstationarity were also observed: 1) multipath component persistence and 2) propagation region transitions. We provide the multipath component probability of occurrence models and describe Markov chains that are used for modeling both phenomena. Channel Tap amplitude statistics are also provided, using the flexible Weibull probability density function (pdf). This pdf was found to best fit fading Tap amplitude data, particularly for frequently observed severe fading, which is characterized by fade probabilities that are worse than the commonly used Rayleigh model. Fading parameters equivalent to Nakagami-m-model values of m near 0.7 were often observed (with m = 1 being Rayleigh and m < 1 being worse than Rayleigh). We also provide Channel Tap amplitude correlation coefficients, which typically range from 0.1 to 0.4 but occasionally take values greater than 0.7.
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The 5-GHz Airport Surface Area Channel—Part I: Measurement and Modeling Results for Large Airports
IEEE Transactions on Vehicular Technology, 2008Co-Authors: David W Matolak, Wenhui XiongAbstract:We describe results from a Channel measurement and modeling campaign for the airport surface environment in the 5-GHz band. Using a 50-MHz bandwidth test signal, thousands of power delay profiles (PDPs) were obtained and processed to develop empirical Tapped-delay line statistical Channel models for large airports. A log-distance path loss model was also developed. The large airport surface Channel is classified into three propagation regions, and models are presented for each of the regions for two values of bandwidth. Values of the median root-mean-square (RMS) delay spread range from 500 to 1000 ns for these airports, with the 90 th percentile RMS delay spreads being approximately 1.7 ms. Corresponding correlation bandwidths (i.e., correlation value 1/2) range from approximately 1.5 MHz in non-line-of-sight (NLOS) settings to 17.5 MHz in line-of-sight (LOS) settings. Two types of statistical nonstationarity were also observed: 1) multipath component persistence and 2) propagation region transitions. We provide the multipath component probability of occurrence models and describe Markov chains that are used for modeling both phenomena. Channel Tap amplitude statistics are also provided, using the flexible Weibull probability density function (pdf). This pdf was found to best fit fading Tap amplitude data, particularly for frequently observed severe fading, which is characterized by fade probabilities that are worse than the commonly used Rayleigh model. Fading parameters equivalent to Nakagami-m-model values of m near 0.7 were often observed (with m = 1 being Rayleigh and m < 1 being worse than Rayleigh). We also provide Channel Tap amplitude correlation coefficients, which typically range from 0.1 to 0.4 but occasionally take values greater than 0.7.
Chunshen Tsai - One of the best experts on this subject based on the ideXlab platform.
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cooperative detection of primary user emulation attacks based on Channel Tap power in mobile cognitive radio networks
Ubiquitous Computing, 2014Co-Authors: Wen-long Chin, Trong Nghia Le, Chunlin Tseng, Chunshen TsaiAbstract:This work proposes a new method for identifying a primary user emulation attack PUEA at low signal-to-noise ratios SNRs in mobile cognitive radio CR networks. Channel-Tap power is utilised as a radio-frequency RF fingerprint to directly detect users via physical PHY layer. To improve the detection performance in fading Channels, the cooperative detection schemes using the fixed sample size test FSST and the sequential probability ratio test SPRT are devised. From simulation results, for a mobile CR speed of 70 km/h, SNR = -5 dB and false alarm probability of 0.03, the FSST using 10 cooperative nodes can achieve the detection probability of 0.99, which is increased by 1.94 times that of the single Neyman-Pearson detector. When the SPRT is compared to the FSST, the SPRT only needs less than half of the detection time of the FSST to provide the same detection performance for all SNRs considered.