Power Allocation for Amplify-and-Forward Opportunistic Relaying Systems

Hui HUI  Shihua ZHU  Gangming LV  

IEICE TRANSACTIONS on Communications   Vol.E92-B   No.11   pp.3541-3545
Publication Date: 2009/11/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E92.B.3541
Print ISSN: 0916-8516
Type of Manuscript: LETTER
Category: Wireless Communication Technologies
cooperative communication,  amplify-and-forward,  power allocation,  outage probability,  

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In this letter, power allocation methods are devised for Amplify-and-Forward (AF) opportunistic relaying systems aiming at minimizing the outage probability. First, we extend the result on outage probability in and develop an approximate expression to simplify the power allocation problem. A corresponding optimization problem is constructed and proved to be convex. Then an iterative numerical method is proposed to find the optimal power allocation factor. We also propose a near-optimal method which can directly calculate the power allocation factor to reduce computational complexity. Numerical results show that the proposed methods have a similar performance with the ideal one, and outperform equal power allocation significantly with little overhead.