Sequential Compensation of RF Impairments in OFDM Systems

Direct-conversion OFDM transceivers are seriously affected by front-end distortions like IQ imbalance and phase noise. Moreover, OFDM systems are sensitive to nonlinear distortions in power amplifiers and A/D converters, and to carrier frequency offset (CFO). We present a novel baseband compensation technique that compensates these main impairments in OFDM systems. Unlike compensation scheme that target a subset of impairments, our method jointly mitigates the effects of IQ imbalance, phase noise, carrier frequency offset and nonlinear distortion. Simulations of the proposed scheme with large levels of CFO, IQ imbalance and phase noise show an excellent performance in terms of bit error rate.