Power Allocation for Energy Efficiency Maximization in DAS with Imperfect CSI and Multiple Receive Antennas

Weiye XU  Min LIN  Ying WANG  Fei WANG  

IEICE TRANSACTIONS on Communications   Vol.E101-B   No.5   pp.1270-1279
Publication Date: 2018/05/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2016EBP3371
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
distributed antenna system,  power allocation,  Imperfect channel state information,  energy efficiency,  multiple receive antenna,  average transmission rate,  

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Based on imperfect channel state information (CSI), the energy efficiency (EE) of downlink distributed antenna systems (DASs) with multiple receive antennas is investigated assuming composite Rayleigh fading channels. A new EE is introduced which is defined as the ratio of the average transmission rate to the total consumed power. According to this definition, an optimal power allocation (PA) scheme is developed for maximizing EE in a DAS subject to the maximum transmit power constraint. It is shown that a PA solution for the constrained EE optimization does exist and is unique. A Newton method based practical iterative algorithm is presented to solve PA. To avoid the iterative calculation, a suboptimal PA scheme is derived by means of the Lambert function, which yields a closed-form PA. The developed schemes include the ones under perfect CSI as special cases, and only need the statistical CSI. Thus, they have low overhead and good robustness. Moreover, the theoretical EE under imperfect CSI is derived for performance evaluation, and the resulting closed-form EE expression is obtained. Simulation results indicate that the theoretical EE can match the corresponding simulated value well, and the developed suboptimal scheme has performance close to optimal one, but with lower complexity.