Performance of OFDM in Radio Mobile Channel
The OFDM has emerged in the second half of last century. However, it remains a technique used in broadband wireless communication systems. Which limits its use is its vulnerability to frequency shifts. The Doppler effect and imperfections of the local oscillators of the transmitter and receiver are at the origin of these shifts. The imperfections of local oscillators shift the spectrum of the OFDM signal, while the Doppler-effect expands it (or compresses it). In this paper, the impact of the Doppler-effect on the OFDM modulation is analyzed, we give a new expression of the contribution of each sub-carrier at the transmitter on each subcarrier demodulated at the receiver. Using the method of inter-carrier interference self-cancellation proposed by Zhao and Haggman, the system becomes more efficient.
KeywordsOrthogonal frequency division multiplexing (OFDM) carrier frequency offset (CFO) Doppler effect Inter carriers Interferences (ICI) carrier to interferences ratio (CIR)
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