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23
Space division multiple access with a sum feedback rate constraint
 IEEE Trans. Signal Processing
, 2007
"... Abstract—On a multiantenna broadcast channel, simultaneous transmission to multiple users by joint beamforming and scheduling is capable of achieving high throughput, which grows double logarithmically with the number of users. The sum rate for channel state information (CSI) feedback, however, incr ..."
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Cited by 34 (7 self)
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Abstract—On a multiantenna broadcast channel, simultaneous transmission to multiple users by joint beamforming and scheduling is capable of achieving high throughput, which grows double logarithmically with the number of users. The sum rate for channel state information (CSI) feedback, however, increases linearly with the number of users, reducing the effective uplink capacity. To address this problem, a novel space division multiple access (SDMA) design is proposed, where the sum feedback rate is upper bounded by a constant. This design consists of algorithms for CSI quantization, thresholdbased CSI feedback, and joint beamforming and scheduling. The key feature of the proposed approach is the use of feedback thresholds to select feedback users with large channel gains and small CSI quantization errors such that the sum feedback rate constraint is satisfied. Despite this constraint, the proposed SDMA design is shown to achieve a sum capacity growth rate close to the optimal one. Moreover, the feedback overflow probability for this design is found to decrease exponentially with the difference between the allowable and the average sum feedback rates. Numerical results show that the proposed SDMA design is capable of attaining higher sum capacities than existing ones, even though the sum feedback rate is bounded. Index Terms—Broadcast channels, feedback communication, multiuser channels, space division multiplexing. I.
SDMA with a sum feedback rate constraint
 Signal Processing; available at ArXiv: http://arxiv.org/abs/cs.IT/0609030
, 2006
"... Abstract — Space division multiple access (SDMA) is capable of achieving sum capacity that grows double logarithmically with the number of users. The sum rate for channel state information (CSI) feedback, however, increases linearly with the number of users, reducing the effective uplink capacity. T ..."
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Cited by 12 (8 self)
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Abstract — Space division multiple access (SDMA) is capable of achieving sum capacity that grows double logarithmically with the number of users. The sum rate for channel state information (CSI) feedback, however, increases linearly with the number of users, reducing the effective uplink capacity. To address this problem, a novel SDMA design is proposed, where the sum feedback rate is upperbounded by a constant. This design consists of algorithms for CSI quantization, threshold based CSI feedback, and joint beamforming and scheduling. The key feature of the proposed approach is the use of feedback thresholds to select feedback users with large channel gains and small CSI quantization errors such that the sum feedback rate constraint is satisfied. Despite this constraint, the proposed SDMA design is shown to achieve a sum capacity growth rate close to the optimal one. Numerical results show that the proposed SDMA design is capable of attaining higher sum capacities than existing ones, even though the sum feedback rate is bounded.
Multiuser diversity gain in cognitive networks with distributed spectrum access,”
 in Proceedings of the 43rd Annual Conference on Information Sciences and Systems (CISS ’09),
, 2009
"... AbstractOpportunistic allocation of resources to the best link in large multiuser networks offers considerable improvement in spectral efficiency, which is often referred to as multiuser diversity gain and can be cast as double logarithmic growth of the network throughput with the number of users. ..."
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Cited by 9 (0 self)
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AbstractOpportunistic allocation of resources to the best link in large multiuser networks offers considerable improvement in spectral efficiency, which is often referred to as multiuser diversity gain and can be cast as double logarithmic growth of the network throughput with the number of users. In this paper we consider large decentralized cognitive networks granted concurrent spectrum access with licenseholding users. We assume that the primary network affords to accommodate one secondary user per any underutilized spectrum band and seek allocating such spectrum bands to a subset of the existing secondary users. We first consider the optimal spectrumsecondary user pairing, which is supervised by a central entity fully aware of the instantaneous channel conditions, and show that the throughput of the cognitive network scales double logarithmically with the number of secondary users (N) and linearly with the number of available spectrum bands (M), i.e. M log log N. Next, we propose a distributed spectrum allocation scheme, which does not necessitate a central controller or any information exchange between different secondary users and obeys the optimal throughput scaling law. This scheme requires that some secondary transmitterreceiver pairs exchange log M information bits among themselves. We also show that the aggregate amount of information exchange between secondary transmitterreceiver secondary pairs is also asymptotically equal to M log M. Finally, we show that our distributed scheme, also guarantees fairness among the secondary users, meaning that they are equally likely to get access to an available spectrum band.
Wireless Energy and Information Transfer Tradeoff for Limited Feedback MultiAntenna Systems with
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Scheduling for Multiuser MIMO Downlink Channels with RankingBased Feedback
, 2008
"... We consider a multiantenna broadcast channel with more singleantenna receivers than transmit antennas and partial channel state information at the transmitter (CSIT). We propose a novel type of CSIT representation for the purpose of user selection, coined as rankingbased feedback. Each user calcu ..."
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Cited by 7 (0 self)
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We consider a multiantenna broadcast channel with more singleantenna receivers than transmit antennas and partial channel state information at the transmitter (CSIT). We propose a novel type of CSIT representation for the purpose of user selection, coined as rankingbased feedback. Each user calculates and feeds back the rank, an integer between 1 and W + 1, of its instantaneous channel quality information (CQI) among a set of W past CQI measurements. Apart from reducing significantly the required feedback load, rankingbased feedback enables the transmitter to select users that are on the highest peak (quantile) with respect to their own channel distribution, independently of the distribution of other users. It can also be shown that this feedback metric can restore temporal fairness in heterogeneous networks, in which users’ channels are not identically distributed and mobile terminals experience different average signaltonoise ratio (SNR). The performance of a system that performs user selection using rankingbased CSIT in the context of random opportunistic beamforming is analyzed, and we provide design guidelines on the number of required past CSIT samples and the impact of finite W on average throughput. Simulation results show that feedback reduction of order of 40−50 % can be achieved with negligible decrease in system throughput.
Multiuser Limited Feedback for Wireless MultiAntenna Communication
"... Abstract — For a wireless multiantenna network with a large number of users, the sum capacity scales at most linearly with the number of antennas and double logarithmically the number of users. Achieving this optimal capacity scaling potentially requires feedback of channel state information (CSI) ..."
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Abstract — For a wireless multiantenna network with a large number of users, the sum capacity scales at most linearly with the number of antennas and double logarithmically the number of users. Achieving this optimal capacity scaling potentially requires feedback of channel state information (CSI) from all users, leading to overflow of the feedback channel. This paper proposes a limited feedback strategy that provides feedback control such that a sum CSI feedback rate constraint is satisfied. It is proved that a wireless multiantenna network using the proposed limited feedback strategy achieves the optimal capacity scaling for the broadcast channel. I.
Optimal selective feedback policies for opportunistic beamforming
 IEEE Trans. Inf. Theory
, 2013
"... Abstract—This paper studies the structure of downlink sumrate maximizing selective decentralized feedback policies for opportunistic beamforming under finite feedback constraints on the average number of mobile users feeding back. First, it is shown that any sumrate maximizing selective decentral ..."
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Abstract—This paper studies the structure of downlink sumrate maximizing selective decentralized feedback policies for opportunistic beamforming under finite feedback constraints on the average number of mobile users feeding back. First, it is shown that any sumrate maximizing selective decentralized feedback policy must be a threshold feedback policy. This result holds for all fading channel models with continuous distribution functions. Second, the resulting optimum threshold selection problem is analyzed in detail. This is a nonconvex optimization problem over finitedimensional Euclidean spaces. By utilizing the theory of majorization, an underlying Schurconcave structure in the sumrate function is identified, and the sufficient conditions for the optimality of homogenous threshold feedback policies are obtained. Applications of these results are illustrated for wellknown fading channel models such as Rayleigh, Nakagami, and Rician fading channels. Rather surprisingly, it is shown that using the same threshold value at all mobile users is not always a ratewise optimal feedback strategy, even for a network in which mobile users experience statistically the same channel conditions. For the Rayleigh fading channel model, on the other hand, homogenous threshold feedback policies are proven to be ratewise optimal if multiple orthonormal data carrying beams are used to communicate with multiple mobile users simultaneously. Index Terms—Majorization, opportunistic beamforming (OBF), selective feedback, sumrate, vector broadcast channels. I.
REDUCED FEEDBACK OPPORTUNISTIC AND LAYERED RANDOM BEAMFORMING FOR MIMOOFDMA SYSTEMS
"... This document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: ..."
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Cited by 1 (1 self)
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This document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available:
GarciaLunaAceves, “On the minimum side information of mimo broadcast channel
 in Proc. of European Wireless Conference
"... We introduce a technique to achieve dirty paper coding (DPC) capacity asymptotically with minimum feedback required reported to date in literature. Our approach called interference management, is based on a new multiuser diversity scheme designed for wireless cellular networks. When there are K ante ..."
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We introduce a technique to achieve dirty paper coding (DPC) capacity asymptotically with minimum feedback required reported to date in literature. Our approach called interference management, is based on a new multiuser diversity scheme designed for wireless cellular networks. When there are K antennas at the base station with M mobile users in the cell, the proposed technique only requires K integer numbers related to channel state information (CSI) between mobile users and base station. The encoding and decoding complexity of this scheme is the same as that of pointtopoint communications. In order to guarantee fairness, a new algorithm is proposed which incorporates interference management into existing GSM standard. 1.