The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
David Tse - One of the best experts on this subject based on the ideXlab platform.
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completely stale transmitter Channel State Information is still very useful
IEEE Transactions on Information Theory, 2012Co-Authors: Mohammad Ali Maddahali, David TseAbstract:Transmitter Channel State Information (CSIT) is crucial for the multiplexing gains offered by advanced interference management techniques such as multiuser multiple-input multiple-output (MIMO) and interference alignment. Such CSIT is usually obtained by feedback from the receivers, but the feedback is subject to delays. The usual approach is to use the fed back Information to predict the current Channel State and then apply a scheme designed assuming perfect CSIT. When the feedback delay is large compared to the Channel coherence time, such a prediction approach completely fails to achieve any multiplexing gain. In this paper, we show that even in this case, the completely stale CSI is still very useful. More concretely, we show that in an MIMO broadcast Channel with transmit antennas and receivers each with 1 receive antenna, K/1+1/2+···+1/K (>;1) degrees of freedom is achievable even when the fed back Channel State is completely independent of the current Channel State. Moreover, we establish that if all receivers have independent and identically distributed Channels, then this is the optimal number of degrees of freedom achievable. In the optimal scheme, the transmitter uses the fed back CSI to learn the side Information that the receivers receive from previous transmissions rather than to predict the current Channel State. Our result can be viewed as the first example of feedback providing a degree-of-freedom gain in memoryless Channels.
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completely stale transmitter Channel State Information is still very useful
arXiv: Information Theory, 2010Co-Authors: Mohammad Ali Maddahali, David TseAbstract:Transmitter Channel State Information (CSIT) is crucial for the multiplexing gains offered by advanced interference management techniques such as multiuser MIMO and interference alignment. Such CSIT is usually obtained by feedback from the receivers, but the feedback is subject to delays. The usual approach is to use the fed back Information to predict the current Channel State and then apply a scheme designed assuming perfect CSIT. When the feedback delay is large compared to the Channel coherence time, such a prediction approach completely fails to achieve any multiplexing gain. In this paper, we show that even in this case, the completely stale CSI is still very useful. More concretely, we show that in a MIMO broadcast Channel with $K$ transmit antennas and $K$ receivers each with 1 receive antenna, $\frac{K}{1+1/2+ ...+ \frac{1}{K}} (> 1) $ degrees of freedom is achievable even when the fed back Channel State is completely independent of the current Channel State. Moreover, we establish that if all receivers have independent and identically distributed Channels, then this is the optimal number of degrees of freedom achievable. In the optimal scheme, the transmitter uses the fed back CSI to learn the side Information that the receivers receive from previous transmissions rather than to predict the current Channel State. Our result can be viewed as the first example of feedback providing a degree-of-freedom gain in memoryless Channels.
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completely stale transmitter Channel State Information is still very useful
Allerton Conference on Communication Control and Computing, 2010Co-Authors: Mohammad Ali Maddahali, David TseAbstract:Transmitter Channel State Information (CSIT) is crucial for the multiplexing gains offered by advanced interference management techniques such as multiuser MIMO and interference alignment. Such CSIT is usually obtained by feedback from the receivers, but the feedback is subject to delays. The usual approach is to use the fed back Information to predict the current Channel State and then apply a scheme designed assuming perfect CSIT. When the feedback delay is large compared to the Channel coherence time, such a prediction approach completely fails to achieve any multiplexing gain. In this paper, we show that even in this case, the completely stale CSI is still very useful. More concretely, we showed that in a MIMO broadcast Channel with K transmit antennas and K receivers each with 1 receive antenna, equation (> 1) degrees of freedom is achievable even when the fed back Channel State is completely independent of the current Channel State. Moreover, we establish that if all receivers have identically distributed Channels, then this is the optimal number of degrees of freedom achievable. In the optimal scheme, the transmitter uses the fed back CSI to learn the side Information that the receivers receive from previous transmissions rather than to predict the current Channel State. Our result can be viewed as the first example of feedback providing a degree-of-freedom gain in memoryless Channels.
Mohammad Ali Maddahali - One of the best experts on this subject based on the ideXlab platform.
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on fading broadcast Channels with partial Channel State Information at the transmitter
International Symposium on Wireless Communication Systems, 2012Co-Authors: Ravi Tandon, Antonia M Tulino, Mohammad Ali Maddahali, Vincent H Poor, Shlomo ShamaiAbstract:The two user multiple-input multiple-output (MIMO) broadcast Channel is studied in which the Channel from one of the receivers is known instantaneously and perfectly at the transmitter, whereas the Channel from the other receiver is known in a delayed manner. The degrees of freedom (DoF) region of the two-user (M; N 1 ; N 2 ) - MIMO broadcast Channel under this model is completely characterized. The scheme illustrates the joint utilization of current and past knowledge of the Channel State Information at the transmitter.
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completely stale transmitter Channel State Information is still very useful
IEEE Transactions on Information Theory, 2012Co-Authors: Mohammad Ali Maddahali, David TseAbstract:Transmitter Channel State Information (CSIT) is crucial for the multiplexing gains offered by advanced interference management techniques such as multiuser multiple-input multiple-output (MIMO) and interference alignment. Such CSIT is usually obtained by feedback from the receivers, but the feedback is subject to delays. The usual approach is to use the fed back Information to predict the current Channel State and then apply a scheme designed assuming perfect CSIT. When the feedback delay is large compared to the Channel coherence time, such a prediction approach completely fails to achieve any multiplexing gain. In this paper, we show that even in this case, the completely stale CSI is still very useful. More concretely, we show that in an MIMO broadcast Channel with transmit antennas and receivers each with 1 receive antenna, K/1+1/2+···+1/K (>;1) degrees of freedom is achievable even when the fed back Channel State is completely independent of the current Channel State. Moreover, we establish that if all receivers have independent and identically distributed Channels, then this is the optimal number of degrees of freedom achievable. In the optimal scheme, the transmitter uses the fed back CSI to learn the side Information that the receivers receive from previous transmissions rather than to predict the current Channel State. Our result can be viewed as the first example of feedback providing a degree-of-freedom gain in memoryless Channels.
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completely stale transmitter Channel State Information is still very useful
arXiv: Information Theory, 2010Co-Authors: Mohammad Ali Maddahali, David TseAbstract:Transmitter Channel State Information (CSIT) is crucial for the multiplexing gains offered by advanced interference management techniques such as multiuser MIMO and interference alignment. Such CSIT is usually obtained by feedback from the receivers, but the feedback is subject to delays. The usual approach is to use the fed back Information to predict the current Channel State and then apply a scheme designed assuming perfect CSIT. When the feedback delay is large compared to the Channel coherence time, such a prediction approach completely fails to achieve any multiplexing gain. In this paper, we show that even in this case, the completely stale CSI is still very useful. More concretely, we show that in a MIMO broadcast Channel with $K$ transmit antennas and $K$ receivers each with 1 receive antenna, $\frac{K}{1+1/2+ ...+ \frac{1}{K}} (> 1) $ degrees of freedom is achievable even when the fed back Channel State is completely independent of the current Channel State. Moreover, we establish that if all receivers have independent and identically distributed Channels, then this is the optimal number of degrees of freedom achievable. In the optimal scheme, the transmitter uses the fed back CSI to learn the side Information that the receivers receive from previous transmissions rather than to predict the current Channel State. Our result can be viewed as the first example of feedback providing a degree-of-freedom gain in memoryless Channels.
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completely stale transmitter Channel State Information is still very useful
Allerton Conference on Communication Control and Computing, 2010Co-Authors: Mohammad Ali Maddahali, David TseAbstract:Transmitter Channel State Information (CSIT) is crucial for the multiplexing gains offered by advanced interference management techniques such as multiuser MIMO and interference alignment. Such CSIT is usually obtained by feedback from the receivers, but the feedback is subject to delays. The usual approach is to use the fed back Information to predict the current Channel State and then apply a scheme designed assuming perfect CSIT. When the feedback delay is large compared to the Channel coherence time, such a prediction approach completely fails to achieve any multiplexing gain. In this paper, we show that even in this case, the completely stale CSI is still very useful. More concretely, we showed that in a MIMO broadcast Channel with K transmit antennas and K receivers each with 1 receive antenna, equation (> 1) degrees of freedom is achievable even when the fed back Channel State is completely independent of the current Channel State. Moreover, we establish that if all receivers have identically distributed Channels, then this is the optimal number of degrees of freedom achievable. In the optimal scheme, the transmitter uses the fed back CSI to learn the side Information that the receivers receive from previous transmissions rather than to predict the current Channel State. Our result can be viewed as the first example of feedback providing a degree-of-freedom gain in memoryless Channels.
Robert W Heath - One of the best experts on this subject based on the ideXlab platform.
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capacity analysis of one bit quantized mimo systems with transmitter Channel State Information
IEEE Transactions on Signal Processing, 2015Co-Authors: Jianhua Mo, Robert W HeathAbstract:With bandwidths on the order of a gigahertz in emerging wireless systems, high-resolution analog-to-digital convertors (ADCs) become a power consumption bottleneck. One solution is to employ low resolution one-bit ADCs. In this paper, we analyze the flat fading multiple-input multiple-output (MIMO) Channel with one-bit ADCs. Channel State Information is assumed to be known at both the transmitter and receiver. For the multiple-input single-output Channel, we derive the exact Channel capacity. For the single-input multiple-output and MIMO Channel, the capacity at infinite signal-to-noise ratio (SNR) is found. We also derive upper bound at finite SNR, which is tight when the Channel has full row rank. In addition, we propose an efficient method to design the input symbols to approach the capacity achieving solution. We incorporate millimeter wave Channel characteristics and find the bounds on the infinite SNR capacity. The results show how the number of paths and number of receive antennas impact the capacity.
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multi mode transmission for the mimo broadcast Channel with imperfect Channel State Information
IEEE Transactions on Communications, 2011Co-Authors: Jun Zhang, Marios Kountouris, J G Andrews, Robert W HeathAbstract:This paper proposes an adaptive multi-mode transmission strategy to improve the spectral efficiency achieved in the multiple-input multiple-output (MIMO) broadcast Channel with delayed and quantized Channel State Information. The adaptive strategy adjusts the number of active users, denoted as the transmission mode, to balance transmit array gain, spatial division multiplexing gain, and residual inter-user interference. Accurate closed-form approximations are derived for the achievable rates for different modes, which help identify the active mode that maximizes the average sum throughput for given feedback delay and Channel quantization error. The proposed transmission strategy can be easily combined with round-robin scheduling to serve a large number of users. As instantaneous Channel Information is not exploited, the proposed algorithm cannot provide multiuser diversity gain, but it is still able to provide throughput gain over single-user MIMO at moderate signal-to-noise ratio. In addition, it has a light feedback overhead and only requires feedback of instantaneous Channel State Information from a small number of users. In the system with a feedback load constraint, it is shown that the proposed algorithm provides performance close to that achieved by opportunistic scheduling with instantaneous feedback from a large number of users.
Shlomo Shamai - One of the best experts on this subject based on the ideXlab platform.
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Information bottleneck for an oblivious relay with Channel State Information the scalar case
IEEE International Conference on Science of Electrical Engineering, 2018Co-Authors: Giuseppe Caire, Shlomo Shamai, Antonia M Tulino, Sergio Verdu, Cagkan YaparAbstract:We consider an extension of the Information bottleneck problem where underlying Markov Chain is $X-0-(Y,\ S)-0-Z$, and where $P_{X,S,Y}=P_{X}P_{S}P_{Y|X,S}$ is the joint distribution of a source X, a Channel State S independent of the source, and the Channel output Y of a State-dependent Channel. For the case $Y=SX+N$ with $X, S$ and N Gaussian circularly symmetric, we provide an upper bound and two achievable lower bounds on the Information bottleneck rate. We relate this problem to the case of an oblivious relay with Channel State Information. Our results show that simple symbol-by-symbol relay processing, possibly followed by “entropy coding” (data compression) yields a very effective method, virtually achieving the upper bound on a wide range of relevant system parameters.
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dirty paper coding with partial Channel State Information
International Workshop on Signal Processing Advances in Wireless Communications, 2014Co-Authors: Itsik Bergel, Daniel Yellin, Shlomo ShamaiAbstract:In this paper we study the effect of partial Channel State Information (CSI) on the performance of dirty paper coding (DPC) schemes. We derive a novel lower bound that shows that the effect of the CSI is upper bounded by the effect of an additive white Gaussian noise with an appropriate variance. The bound is proved using a constructive proof that shows that the predicted rates are achievable using high dimensional lattice modulo precoding schemes. Simulation results demonstrate the usefulness of the bound. The derived bound is useful for the characterization of the interference mitigation performance in partial CSI scenarios such as FDD networks with finite rate feedback, uplink downlink capacity balancing in cooperative cellular networks, etc'.
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on fading broadcast Channels with partial Channel State Information at the transmitter
International Symposium on Wireless Communication Systems, 2012Co-Authors: Ravi Tandon, Antonia M Tulino, Mohammad Ali Maddahali, Vincent H Poor, Shlomo ShamaiAbstract:The two user multiple-input multiple-output (MIMO) broadcast Channel is studied in which the Channel from one of the receivers is known instantaneously and perfectly at the transmitter, whereas the Channel from the other receiver is known in a delayed manner. The degrees of freedom (DoF) region of the two-user (M; N 1 ; N 2 ) - MIMO broadcast Channel under this model is completely characterized. The scheme illustrates the joint utilization of current and past knowledge of the Channel State Information at the transmitter.
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on degrees of freedom region of mimo networks without Channel State Information at transmitters
IEEE Transactions on Information Theory, 2012Co-Authors: Chiachi Huang, Shlomo Shamai, Syed A Jafar, Sriram VishwanathAbstract:We study the effect of the absence of Channel knowledge at the transmitters for multiple-input-multiple-output (MIMO) networks. Specifically, we assume perfect Channel State Information at the receivers, no Channel State Information at the transmitter(s), and independent identically distributed (i.i.d.) Rayleigh fading across antennas, users and time slots. We provide the characterization of the degrees of freedom (DoF) region for a 2-user MIMO broadcast Channel. We then provide a DoF region outer bound for a 2-user MIMO interference Channel. This bound is shown to be tight for all possible combinations of the number of antennas at each node except for one case. To analyze the unsolved case, we point out the potential of interference alignment in the 2-user MIMO interference Channel with no Channel State Information at the transmitters. As a byproduct, we explore a special class of MIMO broadcast Channels where the capacity region is established by using the outer bound developed in the DoF analysis.
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on the required accuracy of transmitter Channel State Information in multiple antenna broadcast Channels
Asilomar Conference on Signals Systems and Computers, 2007Co-Authors: Giuseppe Caire, Nihar Jindal, Shlomo ShamaiAbstract:A multiple antenna broadcast Channel (multiple transmit antennas, one antenna at each receiver) with imperfect Channel State Information available to the transmitter is considered. If perfect Channel State Information is available to the transmitter, then a multiplexing gain equal to the minimum of the number of transmit antennas and the number of receivers is achievable. On the other hand, if each receiver has identical fading statistics and the transmitter has no Channel Information, the maximum achievable multiplexing gain is only one. The focus of this paper is on determination of necessary and sufficient conditions on the rate at which CSIT quality must improve with SNR in order for full multiplexing gain to be achievable. The main result of the paper shows that scaling CSIT quality such that the CSIT error is dominated by the inverse of the SNR is both necessary and sufficient to achieve the full multiplexing gain as well as a bounded rate offset (i.e., the sum rate has no negative sub-logarithmic terms) in the compound Channel setting.
Georgios B Giannakis - One of the best experts on this subject based on the ideXlab platform.
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optimizing orthogonal multiple access based on quantized Channel State Information
IEEE Transactions on Signal Processing, 2011Co-Authors: Antonio G Marques, Georgios B Giannakis, Javier RamosAbstract:The performance of systems where multiple users communicate over wireless fading links benefits from Channel-adaptive allocation of the available resources. Different from most existing approaches that allocate resources based on perfect Channel State Information, this work optimizes Channel scheduling along with per user rate and power loadings over orthogonal fading Channels, when both terminals and scheduler rely on quantized Channel State Information. Channel-adaptive policies are designed to optimize an average transmit-performance criterion subject to average quality of service requirements. While the resultant optimal policy per fading realization shows that the individual rate and power loadings can be obtained separately for each user, the optimal scheduling is slightly more complicated. Specifically, per fading realization each Channel is allocated either to a single (winner) user, or to a small group of winner users whose fraction of shared resources is found by solving a linear program. This bimodal scheduling is also the optimal one when the Channels are deterministic. A single scheduling scheme combining both alternatives (modes) becomes possible by smoothing the original disjoint scheme. The smooth scheduling is asymptotically optimal and incurs reduced computational complexity. Different alternatives to obtain the Lagrange multipliers required to implement the Channel-adaptive policies are proposed, including stochastic iterations that are provably convergent and do not require knowledge of the Channel distribution.
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optimizing orthogonal multiple access based on quantized Channel State Information
arXiv: Information Theory, 2009Co-Authors: Antonio G Marques, Georgios B Giannakis, Javier RamosAbstract:The performance of systems where multiple users communicate over wireless fading links benefits from Channel-adaptive allocation of the available resources. Different from most existing approaches that allocate resources based on perfect Channel State Information, this work optimizes Channel scheduling along with per user rate and power loadings over orthogonal fading Channels, when both terminals and scheduler rely on quantized Channel State Information. Channel-adaptive policies are designed to optimize an average transmit-performance criterion subject to average quality of service requirements. While the resultant optimal policy per fading realization shows that the individual rate and power loadings can be obtained separately for each user, the optimal scheduling is slightly more complicated. Specifically, per fading realization each Channel is allocated either to a single (winner) user, or, to a small group of winner users whose percentage of shared resources is found by solving a linear program. A single scheduling scheme combining both alternatives becomes possible by smoothing the original disjoint scheme. The smooth scheduling is asymptotically optimal and incurs reduced computational complexity. Different alternatives to obtain the Lagrange multipliers required to implement the Channel-adaptive policies are proposed, including stochastic iterations that are provably convergent and do not require knowledge of the Channel distribution. The development of the optimal Channel-adaptive allocation is complemented with discussions on the overhead required to implement the novel policies.
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optimum scheduling for orthogonal multiple access over fading Channels using quantized Channel State Information
International Workshop on Signal Processing Advances in Wireless Communications, 2008Co-Authors: Antonio G Marques, Georgios B Giannakis, F J RamosAbstract:The efficiency of multi-access communications over wireless fading links benefits from Channel-adaptive allocation of the available bandwidth and power resources. Different from most existing approaches that allocate resources based on perfect Channel State Information (P-CSI), this work optimizes Channel scheduling and resource allocation over orthogonal fading Channels when user terminals and the scheduler rely on quantized Channel State Information (Q-CSI). The novel unifying approach optimizes an average transmit-performance criterion subject to average quality of service requirements. The resultant optimal policy per fading realization either allocates the entire Channel to a single (winner) user, or, to a small group of winner users whose percentage of shared resources is found by solving a linear program. Both alternatives become possible by smoothing the allocation scheme. The smooth policy is asymptotically optimal and incurs reduced computational complexity.
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link adaptive cooperative communications without Channel State Information
Military Communications Conference, 2006Co-Authors: Tairan Wang, Alfonso Cano, Georgios B GiannakisAbstract:Link-adaptive regeneration (LAR) is a novel relaying strategy other than decode-and-forward (DF) or amplify-and-forward (AF) in user cooperative communications. Requiring simple Channel State Information (CSI) of both the source-relay and the relay-destination links, LAR has been shown to achieve full diversity using coherent modulations. In this paper, we generalize the idea of LAR into differential and non-coherent cooperative transmissions, which do not require CSI at either relays or destination. We prove that full spatial diversity gain can still be achieved in such systems, without incurring the overhead of cyclic redundancy check (CRC) codes. Simulations demonstrate that the proposed scheme is universally applicable to multi-branch and multi-hop cooperation regardless of the constellation size and outperforms existing alternatives.
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Adaptive MIMO-OFDM based on partial Channel State Information
IEEE Transactions on Signal Processing, 2004Co-Authors: Pengfei Xia, Shengli Zhou, Georgios B GiannakisAbstract:Relative to designs assuming no Channel knowledge at the transmitter, considerably improved communications become possible when adapting the transmitter to the intended propagation Channel. As perfect knowledge is rarely available, transmitter designs based on partial (statistical) Channel State Information (CSI) are of paramount importance not only because they are more practical but also because they encompass the perfect- and no-knowledge paradigms. In this paper, we first provide a partial CSI model for orthogonal frequency division multiplexed (OFDM) transmissions over multi-input multi-output (MIMO) frequency-selective fading Channels. We then develop an adaptive MIMO-OFDM transmitter by applying an adaptive two-dimensional (2-D) coder-beamformer we derived recently on each OFDM subcarrier, along with an adaptive power and bit loading scheme across OFDM subcarriers. Relying on the available partial CSI at the transmitter, our objective is to maximize the transmission rate, while guaranteeing a prescribed error performance, under the constraint of fixed transmit-power. Numerical results confirm that the adaptive 2-D space-time coder-beamformer (with two basis beams as the two "strongest" eigenvectors of the Channel's correlation matrix perceived at the transmitter) combined with adaptive OFDM (power and bit loaded with M-ary quadrature amplitude modulated (QAM) constellations) improves the transmission rate considerably.