Title :
On Minimizing the Cubic Metric of OFDM Signals Using Convex Optimization
Author :
Xiaodong Zhu ; Haichao Hu ; Zhonglou Meng ; Jinxiang Xia
Author_Institution :
Nat. Key Lab. of Sci. & Technol. on Commun., Univ. of Electron. Sci. & Technol. of China, Chengdu, China
Abstract :
A main disadvantage of orthogonal frequency division multiplexing (OFDM) signals is the large envelope fluctuation that limits transmitter power efficiency. Peak-to-average power ratio and cubic metric (CM) are two metrics commonly used to quantify this envelope fluctuation, and now the latter is attracting increasing attention as it can more accurately predict the power de-rating of power amplifier. In this paper, convex optimization is introduced to minimize CM, subject to the constraints on error vector magnitude (EVM) and spectral mask. To solve the formulated optimization problem, a customized interior-point method (IPM) is developed. Simulation results verify the high efficiency of the proposed IPM. For an 802.11a compliant OFDM system, subject to the maximum allowed EVM=5%, 10%, 15% and spectral mask constraints, after three iterations the performance gaps between our IPM and the optimal solution are less than 0.2dB for 99.9% of the symbols.
Keywords :
OFDM modulation; convex programming; masks; minimisation; vectors; CM minimization; EVM; IPM; OFDM signal; convex optimization; cubic metric minimization; customized interior-point method; envelope fluctuation; error vector magnitude; formulated optimization problem; iteration method; orthogonal frequency division multiplexing signal; peak-to-average power ratio; power amplifier; power derating prediction; spectral mask; transmitter power efficiency; Convergence; Convex functions; Measurement; Minimization; Optimization; Peak to average power ratio; OFDM; clipping and filtering; convex optimization; peak-to-average power ratio;
Journal_Title :
Broadcasting, IEEE Transactions on
DOI :
10.1109/TBC.2014.2339534