Frequency Offset Estimation Scheme in the Presence of Time-Varying DC Offset for OFDM Direct Conversion Receivers

Anas Muhamad BOSTAMAM
Yukitoshi SANADA

IEICE TRANSACTIONS on Communications   Vol.E90-B    No.10    pp.2884-2890
Publication Date: 2007/10/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e90-b.10.2884
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
direct conversion,  OFDM,  DC offset,  frequency offset,  training sequence,  

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This paper presents a frequency offset estimation scheme for Orthogonal Frequency Division Multiplex (OFDM) direct conversion receivers. The key idea is to use a differential filter for reduction of DC offset. Frequency offset is estimated in the presence of time-varying DC offset. In order to overcome the varying DC levels under automatic gain control (AGC) circuits, a threshold level is set for the output of the differential filter. The proposed compensation scheme offers superior frequency offset estimation when compared with a conventional scheme with a high pass filter.