Frequency Offset Amplify-and-Forward Relay in OFDM System

Ayana SUZUKI  Yukitoshi SANADA  Mamiko INAMORI  

IEICE TRANSACTIONS on Communications   Vol.E94-B    No.12    pp.3289-3295
Publication Date: 2011/12/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E94.B.3289
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Cooperative Communications for Cellular Networks)
OFDM,  diversity,  amplify-and-forward relaying,  

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In the fourth generation mobile communication system, the frequency band higher than the bands already used for IMT-2000 has been assigned. However, the higher radio frequency increases the propagation loss. To cope with the propagation loss, relay transmission has been investigated. In this paper, a transmission diversity scheme with frequency offset in amplify-and-forward (AF) relaying is proposed. In this scheme, the frequency of the OFDM signal is shifted at the relay station. A different amount of frequency offset is given in each relay station and the signals from the relay stations are separated and combined by MMSE detection at the base station. The numerical results obtained through computer simulation show that diversity is realized and the BER performance is improved by 1-2 dB at the BER of 10-2. When the number of the RSs increases, more BER improvement is achieved.