Multi-User Frequency Offset Correction for OFDMA Reverse Link

Jungwoo LEE  

IEICE TRANSACTIONS on Communications   Vol.E95-B    No.7    pp.2481-2484
Publication Date: 2012/07/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E95.B.2481
Print ISSN: 0916-8516
Type of Manuscript: LETTER
Category: Wireless Communication Technologies
frequency synchronization,  frequency offset estimation,  OFDMA,  reverse link,  

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In the reverse link of OFDMA, different users (subcarriers) may have different frequency offsets, which causes severe performance degradation. It is also difficult to estimate/compensate these frequency offsets in the reverse link. Even if the frequency offsets are correctly estimated, the compensation of one subcarrier (or user) may worsen the inter-carrier interference from the frequency offsets of other subcarriers (users). One of the key ideas in this letter is to merge frequency offset compensation into the FFT matrix. The new inverse transform matrix is used in lieu of regular FFT. A single MMSE-based transform is used to perform both inverse Fourier transform and frequency offset compensation. Compared to the conventional methods such as circular convolution, this approach has lower computational complexity with comparable performance.