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ABSTRACT: In this correspondence, a central Wishart multiple input multiple-output (MIMO) K-block fading channel with an information outage probability constraint is studied. Under this block-limited channel condition, we aim to minimize the transmit power required for attaining a given outage probability based on the statistical channel information at the transmitter (SCIT). Using Gaussian approximation to express the probability density function (pdf) of the instantaneous mutual information and by deriving analytically the mean and variance of the mutual information of the MIMO channel, the optimal power allocation can be obtained numerically by a simple one-dimensional sampling method such as dividing rectange (DIRECT).
IEEE Transactions on Communications 05/2009; · 1.68 Impact Factor
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ABSTRACT: In this paper, we aim to develop an energy-efficient multiuser time-division multiple-access (TDMA) system in block-fading (BF), subject to individual user's quality-of-service (QoS) requirements in terms of outage probability, by jointly-adaptive time-sharing and power allocation for the users in accordance with the causal channel side information (CSI) at the transmitter. We first propose a simple closed-form power allocation solution for a single-user BF channel to attain a given outage probability constraint with causal CSI. Then, we construct an optimization problem to permit a joint consideration of power consumptions and QoS requirements of the users, which we solve to obtain a near-optimal solution for users' time-sharing. The two solutions are combined to provide a suboptimal joint solution for adaptive time-sharing and power allocation of the system. Results reveal that the proposed scheme is near-optimal and a significant energy saving of more than 15 (dB) is possible between systems with and without adaptation on time-sharing and/or power allocation.
Global Telecommunications Conference, 2008. IEEE GLOBECOM 2008. IEEE; 01/2009
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IEEE Transactions on Communications. 01/2009; 57:899-905.
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Proceedings of the 69th IEEE Vehicular Technology Conference, VTC Spring 2009, 26-29 April 2009, Hilton Diagonal Mar, Barcelona, Spain; 01/2009
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IEEE Transactions on Wireless Communications. 01/2009; 8:2221-2229.
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ABSTRACT: In this letter, we consider a delay-constrained wireless communication system where a delay constraint is characterized by the information outage probability in a transmission of K-block Rayleigh flat-fading channels. With multiple users, each given an individual delay requirement, this letter aims to minimize the total transmitted power by optimizing jointly the power distribution and the time sharing of a time-division (TD) multiuser system where the transmitter knows only the channel statistics (CST) but the mobile receivers (or users) have perfect knowledge of the channels. A suboptimal solution which utilizes Gaussian approximation with the mean and variance derived on the instantaneous mutual information and convex optimization, is proposed. Numerical results show that the proposed scheme performs nearly the same as the global optimum.
IEEE Transactions on Wireless Communications 04/2008; · 2.59 Impact Factor
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ABSTRACT: This paper addresses a time-division multiple-access (TDMA) multiuser multiple-input multiple-output (MIMO) antenna system in if-block Rayleigh flat-fading. Assuming a downlink channel where users are given individual outage probability constraints and that the transmitter knows the statistical information about the channel, we aim to minimize the overall transmit power for achieving the users' probability constraints by jointly optimizing the users' power allocation and time-sharing (i.e., the number of time slots). The proposed scheme composes of a newly derived formula for power minimization of an individual user and solving a convex problem constructed for joint consideration of the power consumptions and the probability constraints. Results demonstrate that the proposed scheme performs nearly the same as the global optimum with inappreciable difference.
Information, Communications & Signal Processing, 2007 6th International Conference on; 01/2008
