We perform bit-error-rate (BER) analysis of orthogonal frequency division multiplexing (OFDM) systems impaired by both direct current (DC) offset and carrier frequency offset (CFO) in multipath Rayleigh fading channels. Since the performance of OFDM systems is sensitive to the CFO, it is necessary to estimate and correct the CFO at the receiver. The existence of DC offset degrades the performance of CFO estimator and results in large residual CFO after compensation. Moreover, the process of CFO compensation spreads the DC offset energy and causes DC offset interference to all subcarriers. By deriving the BER formula for OFDM systems employing binary phase-shift keying modulation, the dependency of BER on the DC offset, CFO, and estimated CFO is accurately quantified. Simulation results validate the correctness of our theoretical analysis.
