Thuraya M. Al-Qaradaghi, Refat Talib Hussein
1 College of Engineering, Salahaddin University, 2 Electrical Engineering Dept. University of Technology
Abstract:
To avoid the problem of fast channel variations in time, the symbols of an orthogonal design can be
transmitted on neighboring subcarriers of the same Orthogonal Frequency Division Multiplexing (OFDM)
symbol rather than on the same subcarrier of the subsequent OFDM symbols. This also reduces the
transmission delay. Space-Frequency Block Codes (SFBC) avoids the problem of fast time variations. A new
trend of SFBC introduced and examined for flat and frequency-selective channels over various values of
Doppler frequencies and various type of modulation (QPSK, 8-PSK, 16-QAM and 32-QAM). Alamouti code
was applied to a block of the odd and even elements instead of one symbol. The performance comparisons of
bit error probability for the conventional SFBC-OFDM and the proposed one have been presented. As a
result, it can be concluded that the proposed structure achieves much lower bit error rates. MATLAB version
7.4 had been used as a simulation tool.
Keywords- STC, SFBC, OFDM.
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