Symmetric Extension DFT-Based Noise Variance Estimator in OFDMA Systems with Partial Frequency Response

Yi WANG  Qianbin CHEN  Ken LONG  Zu Fan ZHANG  Hong TANG  

IEICE TRANSACTIONS on Communications   Vol.E95-B   No.6   pp.2157-2159
Publication Date: 2012/06/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E95.B.2157
Print ISSN: 0916-8516
Type of Manuscript: LETTER
Category: Wireless Communication Technologies
symmetric extension,  DFT,  OFDMA,  noise variance estimation,  

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A simple DFT-based noise variance estimator for orthogonal frequency division multiplexing access (OFDMA) systems is proposed. The conventional DFT-based estimator differentiates the channel impulse response and noise in the time domain. However, for partial frequency response, its time domain signal will leak to all taps due to the windowing effect. The noise and channel leakage power become mixed. In order to accurately derive the noise power, we propose a novel symmetric extension method to reduce the channel leakage power. This method is based on the improved signal continuity at the boundaries introduced by symmetric extension. Numerical results show that the normalized mean square error (NMSE) of our proposed method is significantly lower than that of the conventional DFT method.