Digital Compensation of RF Imperfections for Broadband Wireless Systems

In this paper we propose a generally applicable frequency-domain equalization and radio frequency (RF) imperfection compensation technique for orthogonal frequency division multiplexing (OFDM) transmission over frequency-selective channels. Radio frequency (RF) imperfections, such as in-phase/quadrature-phase (IQ) imbalance and carrier frequency offset (CFO) are important issues in today´s wireless broadband systems. Due to component imperfections in practical analog electronics such imbalances are unavoidable, resulting in an overall performance degradation of the system. In this paper the joint effect of frequency selective IQ imbalance at both transmitter and receiver end along with CFO is studied for OFDM based transmission. We also consider the general case when the cyclic prefix is not sufficiently long to accommodate the channel impulse response combined with the transmitter and receiver filter, which results in inter-block-interference (IBI) between the OFDM symbols.