The Experts below are selected from a list of 78216 Experts worldwide ranked by ideXlab platform
Robert W. Heath - One of the best experts on this subject based on the ideXlab platform.
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Multiple-Antenna Transmission With Limited Feedback in Device-to-Device Networks
IEEE Wireless Communications Letters, 2016Co-Authors: Jeonghun Park, Robert W. HeathAbstract:We consider an overlay device-to-device network, where each multiple-antenna transmitter sends data to a designated single-antenna receiver by using maximum ratio transmission based on Limited Feedback, and their locations are modeled by a homogeneous Poisson point process. We obtain a lower bound on the optimum number of Feedback bits that maximizes net spectral efficiency, capturing the overall system gain of using Limited Feedback. Our main finding is that the optimum number of Feedback bits scales linearly with the number of transmit antennas and logarithmically with the channel coherence time and the inverse of the node density.
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Predictive Vector Quantization for Multicell Cooperation with Delayed Limited Feedback
IEEE Transactions on Wireless Communications, 2013Co-Authors: Ramya Bhagavatula, Robert W. HeathAbstract:Base station cooperation can use knowledge of the users' channel state information (CSI) at the transmitters to manage co-channel interference. A reasonable way to provide CSI to the base stations is through a finite rate Limited Feedback channel. Existing multicell Limited Feedback techniques require a large amount of Feedback, which incurs an overhead penalty on the uplink. In this paper, a new Feedback approach based on predictive vector quantization (PVQ) is proposed to reduce Feedback requirements in multicell systems and provide high resolution CSI at base stations by exploiting temporal correlation in the channels. Transmitter and receiver structures are proposed to implement predictive Limited Feedback accounting for delay, for signals on the Grassmann manifold. Simulations show that the proposed PVQ framework yields higher sum-rates than memoryless quantization approaches for multicell Limited Feedback, in a cooperative system using intercell interference nulling.
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Interference Coordination: Random Clustering and Adaptive Limited Feedback
IEEE Transactions on Signal Processing, 2013Co-Authors: Salam Akoum, Robert W. HeathAbstract:Interference coordination improves data rates and reduces outages in cellular networks. Accurately evaluating the gains of coordination, however, is contingent upon using a network topology that models realistic cellular deployments. In this paper, we model the base stations locations as a Poisson point process to provide a better analytical assessment of the performance of coordination. Since interference coordination is only feasible within clusters of Limited size, we consider a random clustering process where cluster stations are located according to a random point process and groups of base stations associated with the same cluster coordinate. We assume channel knowledge is exchanged among coordinating base stations, and we analyze the performance of interference coordination when channel knowledge at the transmitters is either perfect or acquired through Limited Feedback. We apply intercell interference nulling (ICIN) to coordinate interference inside the clusters. The feasibility of ICIN depends on the number of antennas at the base stations. Using tools from stochastic geometry, we derive the probability of coverage and the average rate for a typical mobile user. We show that the average cluster size can be optimized as a function of the number of antennas to maximize the gains of ICIN. To minimize the mean loss in rate due to Limited Feedback, we propose an adaptive Feedback allocation strategy at the mobile users. We show that adapting the bit allocation as a function of the signals' strength increases the achievable rate with Limited Feedback, compared to equal bit partitioning. Finally, we illustrate how this analysis can help solve network design problems such as identifying regions where coordination provides gains based on average cluster size, number of antennas, and number of Feedback bits.
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Grassmannian Predictive Coding for Limited Feedback in Multiple Antenna Wireless Systems
arXiv: Information Theory, 2011Co-Authors: Takao Inoue, Robert W. HeathAbstract:Limited Feedback is a paradigm for the Feedback of channel state information in wireless systems. In multiple antenna wireless systems, Limited Feedback usually entails quantizing a source that lives on the Grassmann manifold. Most work on Limited Feedback beamforming considered single-shot quantiza- tion. In wireless systems, however, the channel is temporally correlated, which can be used to reduce Feedback require- ments. Unfortunately, conventional predictive quantization does not incorporate the non-Euclidean structure of the Grassmann manifold. In this paper, we propose a Grassmannian predictive coding algorithm where the differential geometric structure of the Grassmann manifold is used to formulate a predictive vector quantization encoder and decoder. We analyze the quantization error and derive bounds on the distortion attained by the proposed algorithm. We apply the algorithm to a multiuser multiple-input multiple-output wireless system and show that it improves the achievable sum rate as the temporal correlation of the channel increases.
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Predictive Limited Feedback for cooperative transmission
2010 Conference Record of the Forty Fourth Asilomar Conference on Signals Systems and Computers, 2010Co-Authors: Ramya Bhagavatula, Robert W. HeathAbstract:In multicell cooperation, knowledge of the users' channel state information (CSI) at the base stations can be used to improve sum-rates and reduce outages. Users estimate and Feedback CSI of the desired and multiple interfering channels in cooperation-based systems. Existing multicell Limited Feedback techniques are memoryless quantization approaches, which result in large Feedback overhead. In this paper, a novel technique is proposed using predictive vector quantization to reduce Feedback requirements associated with multicell systems by exploiting temporal correlation in channels. An approach to further reduce Feedback overhead by transmitting back only the normalized vector directions is also presented, using linear prediction. Simulations are used to show that the proposed predictive framework yields higher sum-rates with fewer bits as compared to existing multicell Limited Feedback strategies.
Tianyu Wu - One of the best experts on this subject based on the ideXlab platform.
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Robust Precoder Adaptation for MIMO Links With Noisy Limited Feedback
IEEE Transactions on Information Theory, 2009Co-Authors: Tianyu WuAbstract:In this paper, we propose two robust Limited Feedback designs for multiple-input multiple-output (MIMO) adaptation. The first scheme, namely, the combined design jointly optimizes the adaptation, CSIT (channel state information at the transmitter) Feedback as well as index assignment strategies. The second scheme, namely, the decoupled design, focuses on the index assignment problem given an error-free Limited Feedback design. Simulation results show that the proposed framework has significant capacity gain compared to the naive design (designed assuming there is no Feedback error). Furthermore, for large number of Feedback bits C fb, we show that under two-nearest constellation Feedback channel assumption, the MIMO capacity loss (due to noisy Feedback) of the proposed robust design scales like O(Pe2-[( C fb)/(t+1)]) for some positive integer t. Hence, the penalty due to noisy Limited Feedback in the proposed robust design approaches zero as C fb increases.
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Robust Rate, Power and Precoder Adaptation for Slow Fading MIMO Channels with Noisy Limited Feedback
IEEE Transactions on Wireless Communications, 2008Co-Authors: Tianyu WuAbstract:In this paper, we shall focus on a robust joint rate, power and precoder design for MIMO slow fading channels with noisy Limited Feedback. To take into consideration of the potential packet errors, we optimize the system goodput (b/s/Hz successfully delivered to the receiver) with respect to a general model of Limited Feedback error. We show that the codebook design that maximizes the system goodput can be converted to an equivalent "maximin" problem. Numerical results show that the proposed framework can achieve significant goodput gain comparing to various naive designs (designed for error- free Limited Feedback). Simulation results demonstrated the importance of taking the potential CSIT errors into the Limited Feedback design for robust performance.
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robust rate power and precoder adaptation for slow fading mimo channels with noisy Limited Feedback
Global Communications Conference, 2007Co-Authors: Tianyu WuAbstract:Channel state information at transmitter (CSIT) is important for achieving high spectral efficiency in multi-input multi-output(MIMO) wireless systems especially for slow fading channels. In practice, only a Limited number of bits can be allocated to carry the CSIT Feedback, namely the Limited Feedback. Moreover, the Limited CSIT Feedback may suffer from noise on Feedback channel. With the uncertainty on the CSIT, the packet transmitted may be corrupted (packet outage) if the transmitted rate exceeds the instantaneous mutual information. In this paper, we shall focus on a robust joint rate, power and precoder design for MIMO slow fading channels with noisy Limited Feedback. We optimize the system goodput (b/s/Hz successfully delivered to the receiver) with respect to a general model of Limited Feedback error. We show that the codebook design that maximizes the system goodput can be converted to an equivalent "maximin" problem. Numerical results show that the proposed framework can achieve significant goodput gain comparing to various naive designs (designed for error-free Limited Feedback). Simulation results demonstrated the importance of taking the potential CSIT errors into the Limited Feedback design for robust performance.
David James Love - One of the best experts on this subject based on the ideXlab platform.
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On resource allocation in two-way Limited Feedback beamforming systems
2008 Information Theory and Applications Workshop, 2008Co-Authors: David James Love, Chun Kin Au-yeungAbstract:The benefits employing channel state information (CSI) at the transmitter in a multiple antenna wireless link are well documented in the literature. One of the most popular techniques to provide the transmitter with CSI in frequency division duplexing wireless links is by sending a finite number of Feedback bits. However, the effect of the overhead created by these Feedback bits on the link performance is still not well understood. In this paper, we study a specific scenario of Limited Feedback known as Limited Feedback beamforming. We look at the effect of allocating resources to Feedback and the scaling of these resources. Monte Carlo simulations also demonstrate the inherent tradeoff between the forward and reverse links in a wireless system.
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Multiple Antenna Broadcast Channels With Shape Feedback and Limited Feedback
IEEE Transactions on Signal Processing, 2007Co-Authors: Peilu Ding, David James Love, Michael D. ZoltowskiAbstract:In this paper, we consider two different models of partial channel state information at the base station transmitter (CSIT) for multiple antenna broadcast channels: 1) the shape Feedback model where the normalized channel vector of each user is available at the base station and 2) the Limited Feedback model where each user quantizes its channel vector according to a rotated codebook that is optimal in the sense of mean squared error and feeds back the codeword index. This paper is focused on characterizing the sum rate performance of both zero-forcing dirty paper coding (ZFDPC) systems and channel inversion (CI) systems under the given two partial CSIT models. Intuitively speaking, a system with shape Feedback loses the sum rate gain of adaptive power allocation. However, shape Feedback still provides enough channel knowledge for ZFDPC and CI to approach their own optimal throughput in the high signal-to-noise ratio (SNR) regime. As for Limited Feedback, we derive sum rate bounds for both signaling schemes and link their throughput performance to some basic properties of the quantization codebook. Interestingly, we find that Limited Feedback employing a fixed codebook leads to a sum rate ceiling for both schemes for asymptotically high SNR.
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A performance analysis framework for Limited Feedback beamforming in correlated fading
IEEE Communications Letters, 2006Co-Authors: Chun Kin Au-yeung, David James LoveAbstract:Limited or finite rate, Feedback is an efficient way to implement beamforming in multiple antenna systems using frequency division duplexing. Unfortunately, closed-form performance analysis of Limited Feedback beamforming has not been investigated. This paper provides an analytical framework for the correlated Limited Feedback beamforming problem by treating selection of the beamforming vector from the codebook as a multibranch selection problem.
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ICASSP (4) - Multiple Antenna Broadcast Channels With Limited Feedback
2006 IEEE International Conference on Acoustics Speed and Signal Processing Proceedings, 2006Co-Authors: Peilu Ding, David James Love, Michael D. ZoltowskiAbstract:In this paper, we study the Limited Feedback model for partial CSI at the basestation (BS) for multiple antenna broadcast channels: the BS has the knowledge of quantized CSI of each user. We first give a practical Limited Feedback scheme designed for multiple antenna broadcast channels. Then, we study the sum rate performance of zero-forcing dirty paper coding under the proposed Limited Feedback scheme. An upper bound is also derived to get some insight about the impact of the use of Limited Feedback. Interestingly, we find that the systems experience a ceiling effect on the sum rate for a fixed Feedback rate.
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GLOBECOM - Limited Feedback in Multiple Antenna Broadcast Channels
2006Co-Authors: Peilu Ding, David James Love, Michael D. ZoltowskiAbstract:In this paper, we consider Limited Feedback for multiple antenna broadcast channels: each user quantizes its channel vector according to a rotated codebook which is optimal in the sense of mean square error and feeds back the codeword index. The paper is focused on characterizing the sum rate performance of zero-forcing dirty paper coding (ZFDPC) systems under Limited Feedback. We derive sum rate upper bound for systems employing Gaussian random codebooks and minimum distance decoding and link the throughput performance to some basic properties of the quantization codebook. Interestingly, we find that Limited Feedback employing a fixed codebook leads to a sum rate ceiling for asymptotically high SNR. Index Terms— Broadcast channel, multiple antenna, Limited Feedback.
Rashid Ansari - One of the best experts on this subject based on the ideXlab platform.
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unitary precoding and power control in mimo systems with Limited Feedback
Wireless Communications and Networking Conference, 2006Co-Authors: R Yellapantula, Rashid AnsariAbstract:Spatial multiplexing (SM) proves effective in increasing data rate in a narrowband multiple-input multiple-output (MIMO) system. Past work has shown that unitary precoding with Limited Feedback can be used at the transmitter to improve the bit error rate (BER) performance. Further performance gain can be achieved if power control is used along with unitary preceding at the transmitter. In this paper we propose a novel power control scheme called modified spatial-temporal truncated channel inversion (MST-TCI) for Limited Feedback MIMO systems in block Rayleigh fading channels. A low-complexity algorithm called codebook optimum index loading (COIL) is proposed to generate near-optimum codebooks for quantizing MST-TCI power control information. Simulation results show that the proposed scheme significantly outperforms the Limited Feedback unitary precoding scheme
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WCNC - Unitary precoding and power control in MIMO systems with Limited Feedback
IEEE Wireless Communications and Networking Conference 2006. WCNC 2006., 2006Co-Authors: R Yellapantula, Rashid AnsariAbstract:Spatial multiplexing (SM) proves effective in increasing data rate in a narrowband multiple-input multiple-output (MIMO) system. Past work has shown that unitary precoding with Limited Feedback can be used at the transmitter to improve the bit error rate (BER) performance. Further performance gain can be achieved if power control is used along with unitary preceding at the transmitter. In this paper we propose a novel power control scheme called modified spatial-temporal truncated channel inversion (MST-TCI) for Limited Feedback MIMO systems in block Rayleigh fading channels. A low-complexity algorithm called codebook optimum index loading (COIL) is proposed to generate near-optimum codebooks for quantizing MST-TCI power control information. Simulation results show that the proposed scheme significantly outperforms the Limited Feedback unitary precoding scheme
R Yellapantula - One of the best experts on this subject based on the ideXlab platform.
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unitary precoding and power control in mimo systems with Limited Feedback
Wireless Communications and Networking Conference, 2006Co-Authors: R Yellapantula, Rashid AnsariAbstract:Spatial multiplexing (SM) proves effective in increasing data rate in a narrowband multiple-input multiple-output (MIMO) system. Past work has shown that unitary precoding with Limited Feedback can be used at the transmitter to improve the bit error rate (BER) performance. Further performance gain can be achieved if power control is used along with unitary preceding at the transmitter. In this paper we propose a novel power control scheme called modified spatial-temporal truncated channel inversion (MST-TCI) for Limited Feedback MIMO systems in block Rayleigh fading channels. A low-complexity algorithm called codebook optimum index loading (COIL) is proposed to generate near-optimum codebooks for quantizing MST-TCI power control information. Simulation results show that the proposed scheme significantly outperforms the Limited Feedback unitary precoding scheme
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WCNC - Unitary precoding and power control in MIMO systems with Limited Feedback
IEEE Wireless Communications and Networking Conference 2006. WCNC 2006., 2006Co-Authors: R Yellapantula, Rashid AnsariAbstract:Spatial multiplexing (SM) proves effective in increasing data rate in a narrowband multiple-input multiple-output (MIMO) system. Past work has shown that unitary precoding with Limited Feedback can be used at the transmitter to improve the bit error rate (BER) performance. Further performance gain can be achieved if power control is used along with unitary preceding at the transmitter. In this paper we propose a novel power control scheme called modified spatial-temporal truncated channel inversion (MST-TCI) for Limited Feedback MIMO systems in block Rayleigh fading channels. A low-complexity algorithm called codebook optimum index loading (COIL) is proposed to generate near-optimum codebooks for quantizing MST-TCI power control information. Simulation results show that the proposed scheme significantly outperforms the Limited Feedback unitary precoding scheme
