Effect of Frequency Offset in OFDM Systems with Distributed Beamforming

Youchan JEON
Haesoo KIM

IEICE TRANSACTIONS on Communications   Vol.E96-B    No.1    pp.371-374
Publication Date: 2013/01/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E96.B.371
Print ISSN: 0916-8516
Type of Manuscript: LETTER
Category: Wireless Communication Technologies
cooperative communications,  distributed beamforming,  frequency offset,  OFDM,  

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Three synchronization issues, i.e., phase, frequency, and symbol time, have to be properly controlled to achieve distributed beamforming gain. In orthogonal frequency division multiplexing (OFDM) systems, frequency offset in cooperating signals is more important than other synchronization issues since it results in SNR degradation as well as inter-carrier interference (ICI). In this paper, the impact of frequency offset in distributed beamforming is analyzed for OFDM systems. ICI resulting from frequency offset between cooperating signals is also investigated and approximated. Performance degradation due to frequency offset is shown with various numbers of cooperating signals and offset values. We show that frequency offset between cooperating signals is critical in OFDM systems since it leads to interference from the other subcarriers as well as power loss in the desired signal.