The Experts below are selected from a list of 120 Experts worldwide ranked by ideXlab platform
Jun Hwan Lee - One of the best experts on this subject based on the ideXlab platform.
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NEW2AN - Performance Analysis for DM-RS Mapping in a High Speed Train System
Lecture Notes in Computer Science, 2018Co-Authors: Jihyung Kim, Juho Park, Junghoon Lee, Jun Hwan LeeAbstract:In this paper, we analyze performances for BLER and spectral efficiency in a high speed train (HST) system. The HST scenario is one of 5G mobile communication services. The performance analysis is evaluated in accordance with DM-RS mapping for Channel estimation. DM-RS mapping is associated with high Doppler and frequency flat Channel properties of the HST scenario. The performance results show that DM-RS in new radio (NR) satisfies the performance requirement of HST in ITU-R and a modified DM-RS mapping can be more efficient in HST Channel properties.
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performance analysis for dm rs mapping in a high speed train system
NEW2AN, 2018Co-Authors: Jihyung Kim, Juho Park, Junghoon Lee, Jun Hwan LeeAbstract:In this paper, we analyze performances for BLER and spectral efficiency in a high speed train (HST) system. The HST scenario is one of 5G mobile communication services. The performance analysis is evaluated in accordance with DM-RS mapping for Channel estimation. DM-RS mapping is associated with high Doppler and frequency flat Channel properties of the HST scenario. The performance results show that DM-RS in new radio (NR) satisfies the performance requirement of HST in ITU-R and a modified DM-RS mapping can be more efficient in HST Channel properties.
Shahram Shahbazpanahi - One of the best experts on this subject based on the ideXlab platform.
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Semi-Blind Time-Domain Channel Estimation for Frequency-Selective Multiuser Massive MIMO Systems
IEEE Transactions on Communications, 2019Co-Authors: Javad Mirzaei, Raviraj S. Adve, Shahram ShahbazpanahiAbstract:The availability of accurate Channel state information (CSI) is essential in multiuser massive multiple-input multiple-output (MIMO) systems. However, most published works focus on Frequency-Flat Channel estimation which requires that the estimation must be repeated for every frequency slot, e.g., subcarrier, in a broadband system. Since the Channels in the frequency-domain are the Fourier transform of a small set of time-domain Channel coefficients, the time-domain Channel estimation requires that fewer parameters be estimated. In this paper, we propose a semi-blind, time-domain, Channel estimation technique for frequency-selective massive MIMO systems. Our solution depends on the subspace spanned by the signal eigenvectors of the received signal covariance matrix. Importantly, since the receiver samples at the symbol rate, time-domain-based estimation inherently has available enough samples for an accurate matrix estimate. To avoid asymptotic assumptions, we express each Channel vector as a linear combination of the signal eigenvectors. We estimate the linear combination using a set of training symbols. Given the many samples of the received signal in the time-domain, we obtain a better Channel estimate compared to conventional subcarrier-wise frequency-domain Channel estimation. Unlike the previous published results, in this paper, we do not assume orthogonality of users’ Channels or knowledge of large-scale fading coefficients. In addition, our estimation procedure does not require orthogonality between the training symbols of the users in all cells.
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GLOBECOM - Semi-Blind Channel Estimation for Frequency-Selective Massive MIMO Systems
2018 IEEE Global Communications Conference (GLOBECOM), 2018Co-Authors: Javad Mirzaei, Raviraj S. Adve, Shahram ShahbazpanahiAbstract:Channel state information (CSI) is essential in massive multiple-input mulitple-output (MIMO) systems. However, most of the literature focuses on Frequency-Flat Channel estimation; in a realistic broadband setting this implies that the estimation must be repeated for each subcarrier. In this paper, we propose a new Channel estimation technique for frequency-selective Channels in the time-domain. Time-domain CSI acquisition requires the estimation of fewer parameters. Importantly, since the receiver samples at the symbol rate, time-domain based estimation yields many samples of the received signal. Our approach depends on the estimation of the subspace spanned by users' Channels, requiring a large number of antennas to ensure that the required rank constraints are met. Unlike previous published results, in this paper, we do not make any assumption on orthogonality of users' Channel vectors or knowledge of large-scale fading coefficients. Additionally, our Channel estimation, does not require orthogonality between the training symbols of the users in all cells.
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EUSIPCO - Single-carrier equalization and distributed beamforming for asynchronous two-way relay networks
2013Co-Authors: Reza Vahidnia, Shahram ShahbazpanahiAbstract:In this paper, we consider a single-carrier communication scheme, where two transceivers exchange information with the help of multiple relays. The propagation delay in each relaying path is assumed to be different from those of the other paths. As such, the end-to-end Channel is frequency selective, and hence, it produces inter-symbol-interference (ISI) at the two transceivers. The simple amplify-and-forward scheme is used at the relays and Channel equalization is employed at both transceivers to combat ISI. We minimize the mean square error (MSE) of the total estimated received signals at the both transceivers, subject to a total power budget constraint, by optimizing the Channel equalizers, the relay beamforming weights, and the transceivers' powers. We show that our proposed approach leads to a relay selection method which transforms the end-to-end Channel into a frequency flat Channel. We also present a semi-closed-form solution for the optimal relay beamforming weight.
Yahong Rosa Zheng - One of the best experts on this subject based on the ideXlab platform.
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On the Ergodic Capacity of MIMO Triply Selective Rayleigh Fading Channels
IEEE Transactions on Wireless Communications, 2008Co-Authors: Chengshan Xiao, Yahong Rosa ZhengAbstract:The ergodic capacity is investigated for triply selective MIMO Rayleigh fading Channels. A mathematical formula is derived for the ergodic capacity in the case when the Channel state information is known to the receiver but unknown to the transmitter. A closed-form formula is derived that quantifies the effect of the frequency-selective fading on the ergodic capacity into an intersymbol interference (ISI) degradation factor. Different from the existing conclusion that the frequency-selective fading Channel has the same ergodic capacity as the frequency flat fading Channel, we show that the discrete-time inter-tap correlated frequency-selective fading Channel has smaller ergodic capacity than the frequency flat fading Channel. Only in the special case when the fading does not have ISI inter-tap correlations will the ergodic capacity be the same as that of the frequency flat Channel. Theoretical derivation and computer simulation demonstrate that the inter-tap correlations can have more significant impact on the ergodic capacity than the spatial correlations.
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WCNC - Ergodic capacity of doubly selective Rayleigh fading MIMO Channels
2004 IEEE Wireless Communications and Networking Conference (IEEE Cat. No.04TH8733), 2004Co-Authors: Chengshan Xiao, Yahong Rosa ZhengAbstract:The ergodic capacity is investigated for doubly selective (frequency selective and time varying) MIMO Rayleigh fading Channels. A closed form formula is derived that quantifies the effect of the ISI fading on the ergodic capacity into an ISI degradation factor. It is discovered that, in general frequency selective MIMO Channels, the inter-tap correlations of the ISI fading will reduce the ergodic capacity comparing to the frequency flat fading Channel. Only in the special case when the ISI fading does not have inter-tap correlations will the ergodic capacity be the same as that of the frequency flat Channel. This new formula is mathematically proved and experimentally verified via Monte-Carlo simulations.
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GLOBECOM - Ergodic capacity of MIMO triply selective Rayleigh fading Channels
IEEE Global Telecommunications Conference 2004. GLOBECOM '04., 1Co-Authors: Chengshan Xiao, Yahong Rosa ZhengAbstract:New results are presented for the ergodic capacity of spatially-correlated, time-varying and frequency-selective (i.e., triply selective) MIMO Rayleigh fading Channels. Simplified capacity formulas are also derived for special cases such as SIMO and MISO triply selective fading Channels. A closed form formula is proposed that quantifies the effect of the frequency-selective fading on the ergodic capacity into an intersymbol interference (ISI) degradation factor. It is discovered that, in general frequency-selective MIMO Channels, the ISI inter-tap correlations reduce the ergodic capacity compared to the frequency flat fading Channel. Only in the special case when the fading does not have ISI inter-tap correlations will the ergodic capacity be the same as that of the frequency flat Channel. The new capacity results are experimentally verified via Monte-Carlo simulations.
Alexei Gorokhov - One of the best experts on this subject based on the ideXlab platform.
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Antenna selection algorithms for MEA transmission systems
2002 IEEE International Conference on Acoustics, Speech, and Signal Processing, 2002Co-Authors: Alexei GorokhovAbstract:The use of multiple element antennas (MEA) at the transmitter and receiver offers a possibility to substantially increase the throughput of a fading Channel. Recent publications show that for a moderate number of transmit/receive subChannels, the outage throughput of MEA transceivers improves substantially when a big set of transmit or/and receive antennas is available to select a suitable subset of antennas which is subject to Channel realisation. Optimal subset selection is, however, numerically intensive and hardly feasible for a big number of antennas and a moderate number of subChannels. In this contribution, we present a suboptimal selection algorithm which yields an important complexity reduction and may enable a real-time selection. Numerical results suggest that such a sub-optimal selection yields a negligible loss compared to the optimal strategy in the case of frequency flat Channel. A possible extension for frequency selective Channels is also indicated.
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ICASSP - Antenna selection algorithms for MEA transmission systems
IEEE International Conference on Acoustics Speech and Signal Processing, 2002Co-Authors: Alexei GorokhovAbstract:The use of multiple element antennas (MEA) at the transmitter and receiver offers a possibility to substantially increase the throughput of a fading Channel. Recent publications show that for a moderate number of transmit/receive subChannels, the outage throughput of MEA transceivers improves substantially when a big set of transmit or/and receive antennas is available to select a suitable subset of antennas which is subject to Channel realisation. Optimal subset selection is, however, numerically intensive and hardly feasible for a big number of antennas and a moderate number of subChannels. In this contribution, we present a suboptimal selection algorithm which yields an important complexity reduction and may enable a real-time selection. Numerical results suggest that such a sub-optimal selection yields a negligible loss compared to the optimal strategy in the case of frequency flat Channel. A possible extension for frequency selective Channels is also indicated.
Jihyung Kim - One of the best experts on this subject based on the ideXlab platform.
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NEW2AN - Performance Analysis for DM-RS Mapping in a High Speed Train System
Lecture Notes in Computer Science, 2018Co-Authors: Jihyung Kim, Juho Park, Junghoon Lee, Jun Hwan LeeAbstract:In this paper, we analyze performances for BLER and spectral efficiency in a high speed train (HST) system. The HST scenario is one of 5G mobile communication services. The performance analysis is evaluated in accordance with DM-RS mapping for Channel estimation. DM-RS mapping is associated with high Doppler and frequency flat Channel properties of the HST scenario. The performance results show that DM-RS in new radio (NR) satisfies the performance requirement of HST in ITU-R and a modified DM-RS mapping can be more efficient in HST Channel properties.
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performance analysis for dm rs mapping in a high speed train system
NEW2AN, 2018Co-Authors: Jihyung Kim, Juho Park, Junghoon Lee, Jun Hwan LeeAbstract:In this paper, we analyze performances for BLER and spectral efficiency in a high speed train (HST) system. The HST scenario is one of 5G mobile communication services. The performance analysis is evaluated in accordance with DM-RS mapping for Channel estimation. DM-RS mapping is associated with high Doppler and frequency flat Channel properties of the HST scenario. The performance results show that DM-RS in new radio (NR) satisfies the performance requirement of HST in ITU-R and a modified DM-RS mapping can be more efficient in HST Channel properties.
