Effect of carrier frequency offset on time-domain differential demodulation in OFDM systems

This paper analyzes the effect of the carrier frequency offset on time-domain differential demodulation in orthogonal frequency division multiplexing (OFDM) systems. Exact signal-to-noise ratio (SNR) and accurate symbol error rate (SER) expressions are derived in the presence of the frequency offset. Using the SNR expression, the SNR degradation due to the frequency offset is quantified. The effect of the frequency offset on time-domain differential demodulation is compared with that on coherent demodulation. It is found that time-domain differential demodulation is more sensitive to carrier frequency offsets compared to coherent demodulation. The analysis in this paper not only provides insights into how the carrier frequency offset affects the system performance, but can also be used to determine the maximum tolerable frequency offset given a target SER.