Exponential Diversity Achieving Spatio–Temporal Power Allocation Scheme for Fading Channels

Sharma, Vinod and Premkumar, Karumbu and Swamy, Raghava N (2008) Exponential Diversity Achieving Spatio–Temporal Power Allocation Scheme for Fading Channels. In: IEEE Transactions on Information Theory, 54 (1). pp. 188-208.

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Abstract

In this paper, we analyze optimal (in space and time) adaptive power transmission policies for fading channels when the channel-state information (CSI) at the transmitter (CSIT) and the receiver (CSIR) is available. The transmitter has a long-term (time) average power constraint. There can be multiple antennas at the transmitter and at the receiver. The channel experiences Rayleigh fading. We consider beamforming and space–time coded systems with perfect/imperfect CSIT and CSIR. The performance measure is the bit error rate (BER). We show that in both coded and uncoded systems, our power allocation policy provides exponential diversity order if perfect CSIT is available. We also show that, if the quality of CSIT degrades then the exponential diversity is retained in the low SNR region but we get only polynomial diversity in the high SNR region. Another interesting conclusion is that in case of imperfect CSIT and CSIR, knowledge of CSIT at the receiver is very important. Finally, for the optimal power control policy of the uncoded system we find the error-exponents which provide the rate versus diversity-order tradeoff for this policy. This tradeoff is of an entirely different nature than the well-known Zheng–Tse tradeoff.

Item Type:	Journal Article
Publication:	IEEE Transactions on Information Theory
Publisher:	IEEE
Additional Information:	©2008 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.
Keywords:	Beamforming;channel-state information receiver (CSIR);channel-state information transmitter (CSIT);convolutional codes;error exponents;fading channels;power allocation;rate versus diversity order tradeoff;space–time codes.
Department/Centre:	Division of Electrical Sciences > Electrical Communication Engineering
Date Deposited:	13 Jun 2008
Last Modified:	19 Sep 2010 04:45
URI:	http://eprints.iisc.ac.in/id/eprint/14270

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