The Experts below are selected from a list of 59664 Experts worldwide ranked by ideXlab platform
Bruno Clerckx - One of the best experts on this subject based on the ideXlab platform.
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mimo systems with limited rate differential Feedback in slowly varying channels
IEEE Transactions on Communications, 2011Co-Authors: Taejoon Kim, David J Love, Bruno ClerckxAbstract:In this paper, an adaptive limited Feedback linear precoding technique for temporally correlated multiple-input multiple-output (MIMO) channels is proposed, where the receiver has perfect channel knowledge but the transmitter only receives a quantized channel direction. To perform adaptation to the time correlation structure, we employ a differential Feedback, where the "amount" of the perturbation added to the previous precoder is determined by the statistics of the directional variation. Based on random matrix quantization analysis, we develop a spherical cap codebook approach, where the cap is centered at the previous precoder and the radius of the cap is determined proportional to the identified directional variation. If the channel is highly correlated in time, it is shown that the proposed differential Feedback Scheme achieves significant throughput improvement in the large codebook size regime. The rest of the paper is devoted to developing a systematic spherical cap codebook generation method. The developed approach employs a Feedback Scheme that uses a differential rotation of the previously used precoder. Our codebook adaptation is based on generating a perturbation in Euclidean space and projecting the perturbation onto the unitary space. Simulation results show that the proposed adaptation Scheme accurately tracks the channel using only a small rate of Feedback.
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mimo systems with limited rate differential Feedback in slowly varying channels
IEEE Transactions on Communications, 2011Co-Authors: David J Love, Bruno ClerckxAbstract:In this paper, an adaptive limited Feedback linear precoding technique for temporally correlated multiple-input multiple-output (MIMO) channels is proposed, where the receiver has perfect channel knowledge but the transmitter only receives a quantized channel direction. To perform adaptation to the time correlation structure, we employ a differential Feedback, where the "amount" of the perturbation added to the previous precoder is determined by the statistics of the directional variation. Based on random matrix quantization analysis, we develop a spherical cap codebook approach, where the cap is centered at the previous precoder and the radius of the cap is determined proportional to the identified directional variation. If the channel is highly correlated in time, it is shown that the proposed differential Feedback Scheme achieves significant throughput improvement in the large codebook size regime. The rest of the paper is devoted to developing a systematic spherical cap codebook generation method. The developed approach employs a Feedback Scheme that uses a differential rotation of the previously used precoder. Our codebook adaptation is based on generating a perturbation in Euclidean space and projecting the perturbation onto the unitary space. Simulation results show that the proposed adaptation Scheme accurately tracks the channel using only a small rate of Feedback.
David J Love - One of the best experts on this subject based on the ideXlab platform.
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mimo systems with limited rate differential Feedback in slowly varying channels
IEEE Transactions on Communications, 2011Co-Authors: Taejoon Kim, David J Love, Bruno ClerckxAbstract:In this paper, an adaptive limited Feedback linear precoding technique for temporally correlated multiple-input multiple-output (MIMO) channels is proposed, where the receiver has perfect channel knowledge but the transmitter only receives a quantized channel direction. To perform adaptation to the time correlation structure, we employ a differential Feedback, where the "amount" of the perturbation added to the previous precoder is determined by the statistics of the directional variation. Based on random matrix quantization analysis, we develop a spherical cap codebook approach, where the cap is centered at the previous precoder and the radius of the cap is determined proportional to the identified directional variation. If the channel is highly correlated in time, it is shown that the proposed differential Feedback Scheme achieves significant throughput improvement in the large codebook size regime. The rest of the paper is devoted to developing a systematic spherical cap codebook generation method. The developed approach employs a Feedback Scheme that uses a differential rotation of the previously used precoder. Our codebook adaptation is based on generating a perturbation in Euclidean space and projecting the perturbation onto the unitary space. Simulation results show that the proposed adaptation Scheme accurately tracks the channel using only a small rate of Feedback.
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mimo systems with limited rate differential Feedback in slowly varying channels
IEEE Transactions on Communications, 2011Co-Authors: David J Love, Bruno ClerckxAbstract:In this paper, an adaptive limited Feedback linear precoding technique for temporally correlated multiple-input multiple-output (MIMO) channels is proposed, where the receiver has perfect channel knowledge but the transmitter only receives a quantized channel direction. To perform adaptation to the time correlation structure, we employ a differential Feedback, where the "amount" of the perturbation added to the previous precoder is determined by the statistics of the directional variation. Based on random matrix quantization analysis, we develop a spherical cap codebook approach, where the cap is centered at the previous precoder and the radius of the cap is determined proportional to the identified directional variation. If the channel is highly correlated in time, it is shown that the proposed differential Feedback Scheme achieves significant throughput improvement in the large codebook size regime. The rest of the paper is devoted to developing a systematic spherical cap codebook generation method. The developed approach employs a Feedback Scheme that uses a differential rotation of the previously used precoder. Our codebook adaptation is based on generating a perturbation in Euclidean space and projecting the perturbation onto the unitary space. Simulation results show that the proposed adaptation Scheme accurately tracks the channel using only a small rate of Feedback.
Wolfgang Zirwas - One of the best experts on this subject based on the ideXlab platform.
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Research Article Efficient Feedback via Subspace-Based Channel Quantization for Distributed Cooperative Antenna Systems with Temporally Correlated Channels
2013Co-Authors: Jee Hyun Kim, Wolfgang Zirwas, Martin HaardtAbstract:It is one of the biggest challenges of distributed cooperative antenna (COOPA) systems to provide base stations (BSs) with downlink channel information for transmit filtering (precoding). In this paper, we propose a novel Feedback Scheme via a subspace-based channel quantization method. The proposed Scheme adopts the chordal distance as a channel quantizer criterion so as to capture channel characteristics represented by subspaces spanned by the channel matrix. We also propose a combined Feedback Scheme which is based on the hierarchical codebook construction method in an effort to reduce the Feedback overhead by exploiting the temporal correlation of the channel. The proposed methods are tested for distributed COOPA systems in terms of simulations. Simulation results show that the proposed subspace-based channel quantization method outperforms the analog pilot retransmission method, and the combined Feedback Scheme performs as well as the permanent full-Feedback Scheme with a much smaller amount of uplink resources. Copyright © 2008 Jee Hyun Kim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1
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a unified Feedback Scheme for distributed interference management in cellular systems benefits and challenges for real time implementation
European Signal Processing Conference, 2009Co-Authors: Lars Thiele, T Wirth, Thomas Haustein, Volker Jungnickel, Egon Schulz, Wolfgang ZirwasAbstract:This paper contributes to the system concept of collaborative base stations from the perspective of distributed computing. Promising signal processing approaches based on terminal Feedback are reviewed. Their specific advantages and disadvantages are discussed and a framework for Feedback provision is presented. All proposed Schemes have in common, that a mobile terminal can choose its desired receive strategy independently from other mobile terminals according to its computational capabilities. The effective multi-cell channel after receiver processing is fed back and distributed within the collaboration area. This allows distributed processing at each base station and makes real-time implementation feasible.
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efficient Feedback via subspace based channel quantization for distributed cooperative antenna systems with temporally correlated channels
EURASIP Journal on Advances in Signal Processing, 2008Co-Authors: Jee Hyun Kim, Wolfgang Zirwas, Martin HaardtAbstract:It is one of the biggest challenges of distributed cooperative antenna (COOPA) systems to provide base stations (BSs) with down-link channel information for transmit filtering (precoding). In this paper, we propose a novel Feedback Scheme via a subspace-based channel quantization method. The proposed Scheme adopts the chordal distance as a channel quantizer criterion so as to capture channel characteristics represented by subspaces spanned by the channel matrix. We also propose a combined Feedback Scheme which is based on the hierarchical codebook construction method in an effort to reduce the Feedback overhead by exploiting the temporal correlation of the channel. The proposed methods are tested for distributed COOPA systems in terms of simulations. Simulation results show that the proposed subspace-based channel quantization method outperforms the analog pilot retransmission method, and the combined Feedback Scheme performs as well as the permanent full-Feedback Scheme with a much smaller amount of uplink resources.
Alexander M Haimovich - One of the best experts on this subject based on the ideXlab platform.
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ergodic and outage performance of fading broadcast channels with 1 bit Feedback
IEEE Transactions on Vehicular Technology, 2010Co-Authors: Bo Niu, Osvaldo Simeone, Oren Somekh, Alexander M HaimovichAbstract:In this paper, the ergodic sum rate and the outage probability of a downlink single-antenna channel with K users are analyzed in the presence of Rayleigh flat fading, where limited channel state information (CSI) Feedback is assumed. Specifically, only 1-bit Feedback per fading block per user is available at the base station. We first study the ergodic sum rate of the 1-bit Feedback Scheme and consider the impact of Feedback delay on the system. A closed-form expression for the achievable ergodic sum rate is presented as a function of the fading temporal correlation coefficient. It is proved that the sum rate scales as log log K, which is the same scaling law achieved by the optimal nondelayed full CSI Feedback Scheme. The sum-rate degradation due to outdated CSI is also evaluated in the asymptotic regimes of either large K or low SNR. The outage performance of the 1-bit Feedback Scheme for both instantaneous and outdated Feedback is then investigated. Expressions for the outage probabilities are derived, along with the corresponding diversity-multiplexing tradeoffs (DMTs). It is shown that, with instantaneous Feedback, a power allocation based on the Feedback bits enables doubling of the DMT compared with the case with short-term power constraint in which a dynamic power allocation is not allowed. However, with outdated Feedback, the advantage of power allocation is lost, and the DMT reverts to that achievable with no CSI Feedback. Nevertheless, for finite SNR, improvement in terms of outage probability can still be obtained.
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ergodic and outage performance of fading broadcast channels with 1 bit Feedback
arXiv: Information Theory, 2010Co-Authors: Bo Niu, Osvaldo Simeone, Oren Somekh, Alexander M HaimovichAbstract:In this paper, the ergodic sum-rate and outage probability of a downlink single-antenna channel with K users are analyzed in the presence of Rayleigh flat fading, where limited channel state information (CSI) Feedback is assumed. Specifically, only 1-bit Feedback per fading block per user is available at the base station. We first study the ergodic sum-rate of the 1-bit Feedback Scheme, and consider the impact of Feedback delay on the system. A closed-form expression for the achievable ergodic sum-rate is presented as a function of the fading temporal correlation coefficient. It is proved that the sum-rate scales as loglogK, which is the same scaling law achieved by the optimal non-delayed full CSI Feedback Scheme. The sum-rate degradation due to outdated CSI is also evaluated in the asymptotic regimes of either large K or low SNR. The outage performance of the 1-bit Feedback Scheme for both instantaneous and outdated Feedback is then investigated. Expressions for the outage probabilities are derived, along with the corresponding diversity-multiplexing tradeoffs (DMT). It is shown that with instantaneous Feedback, a power allocation based on the Feedback bits enables to double the DMT compared to the case with short-term power constraint in which a dynamic power allocation is not allowed. But, with outdated Feedback, the advantage of power allocation is lost, and the DMT reverts to that achievable with no CSI Feedback. Nevertheless, for finite SNR, improvement in terms of outage probability can still be obtained.
Younghan Nam - One of the best experts on this subject based on the ideXlab platform.
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transparent operation of kronecker product based full dimension mimo to exploit 2d antenna array
Wireless Communications and Networking Conference, 2016Co-Authors: Suryong Jeong, Md Saifur Rahman, Jiyun Seol, Keonkook Lee, Taeyoung Kim, Younghan NamAbstract:A concept of full-dimension MIMO (FD-MIMO) adopting 2-dimensional (2D) antenna array has been proposed with intent to cope with practical challenges of massive MIMO systems. In this paper, we investigate an FD-MIMO operation that can be transparently applied with current 3GPP LTE specifications, and propose a novel method that facilitates an accurate estimation of channel quality indicator (CQI) at base station (BS). We first introduce a Feedback Scheme in which horizontal and vertical dimension channel information are separately reported. To further improve accuracy of modulation and coding Scheme (MCS) selection to maximize system throughput, we propose an enhanced Feedback Scheme that is helpful to more accurate CQI estimation at the BS. In the evaluation results, we show performance improvement of the proposed Scheme over the conventional MIMO Scheme.
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linear combination codebook based csi Feedback Scheme for fd mimo systems
Global Communications Conference, 2015Co-Authors: Md Saifur Rahman, Younghan Nam, Jianzhong Zhang, Jiyun SeolAbstract:We present an enhanced CSI Feedback Scheme for FD-MIMO systems based on a linear combination codebook. To reduce codebook search complexity, an efficient codebook search method is also provided. Both capacity-based and system-level performance evaluations of the proposed Scheme are conducted and the performance is compared with the Kronecker product codebook based Scheme. The proposed linear combination codebook shows significant performance improvement over the Kronecker product codebook with reasonable increase in Feedback overhead; thereby shows the potential to reduce the performance gap towards the ideal CSI Scheme.
