Optimum Power and Rate Adaptation for MQAM in Rayleigh Flat Fading With Imperfect Channel Estimation

We derive an optimum power and rate adaptation for maximizing the spectral efficiency based on an imperfect channel estimate and subject to average power and instantaneous bit error rate (BER) constraints for multilevel quadrature amplitude modulation (MQAM) over Rayleigh flat-fading channels. The o...

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Vydáno v:	IEEE transactions on vehicular technology Ročník 57; číslo 4; s. 2622 - 2627
Hlavní autoři:	Olfat, A., Shikh-Bahaei, M.
Médium:	Journal Article
Jazyk:	angličtina
Vydáno:	New York, NY IEEE 01.07.2008 Institute of Electrical and Electronics Engineers The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Témata:	Adaptation Amplitude estimation Applied sciences Bit error rate Channel estimation Channels Constellation diagram Constellations Detection, estimation, filtering, equalization, prediction Estimates Exact sciences and technology Fading flat fading Information, signal and communications theory Mathematical analysis Mean square error methods Modulation coding Modulation, demodulation Nonlinear equations Optimization power and rate adaptation Quadrature amplitude modulation Rayleigh channels Signal and communications theory Signal, noise spectral efficiency Studies Systems, networks and services of telecommunications Telecommunications Telecommunications and information theory Teletraffic Transmission and modulation (techniques and equipments) channel estimation Flat fading power and rate adaptation spectral efficiency Fading channels Correlation coefficient Performance evaluation Parameter estimation Quadrature amplitude modulation Bit error rate Flow rate regulation Rayleigh channels Optimization method Teletraffic flat fading Non linear equation M ary modulation Channel estimation Traffic management Optimal solution Traffic control Rayleigh fading Multilevel system Comparative study Gain
ISSN:	0018-9545, 1939-9359
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Popis
Shrnutí:	We derive an optimum power and rate adaptation for maximizing the spectral efficiency based on an imperfect channel estimate and subject to average power and instantaneous bit error rate (BER) constraints for multilevel quadrature amplitude modulation (MQAM) over Rayleigh flat-fading channels. The optimal solution is derived for continuous- and discrete-rate adaptation and is expressed in terms of a specific bounded function that is the solution of a nonlinear equation and cannot be expressed in a closed mathematical form. The optimum power adaptation for the continuous rate is shown to be a generalization of water pouring for that function. It is also shown that the conventional water-pouring (with bias) strategy for power adaptation in the continuous-rate condition is a suboptimum solution of the general optimization problem, and it tends to the optimal solution as the correlation coefficient between the true channel gain and its estimate tends to one. We also show that less than 1 dB power is lost by using discrete-rate MQAM with only six different signal constellations compared to the continuous-rate adaptation with an unconstrained constellation size.
Bibliografie:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 14 content type line 23
ISSN:	0018-9545 1939-9359
DOI:	10.1109/TVT.2007.912172