Abstract-The implementation of orthogonal frequency division multiplexing (OFDM)-based physical layers suffers from the effect of In-phase and Quadrature-phase (IQ) imbalances in the front-end analog processing. The IQ imbalances can severely limit the achievable operating signal-to-noise ratio (SNR) at the receiver and, consequently, the supported constellation sizes and data rates. In this paper, the effect of IQ imbalances on OFDM receivers is studied, and system-level algorithms to compensate for the distortions are proposed. The algorithms include post-fast Fourier transform (FFT) least-squares and least mean squares (LMS) equalization, as well as pre-FFT correction using adaptive channel/distortion estimation and special pilot tones to enable accurate and fast training. Bounds on the achievable performance of the compensation algorithms are derived and evaluated as a function of the physical distortion parameters. A motivation is included for the physical causes of IQ imbalances and for the implications of the approach presented in this paper on designing and implementing wireless transceivers. Index Terms-Compensation algorithms for analog impairments, equalization, in-phase and quadrature-phase (IQ) imbalances, orthogonal frequency division multiplexing (OFDM).
Moreover, estimationbased system-level algorithms, including least square equalization, adaptive equalization, and post-fast Fourier transform least square, were proposed in REF to compensate the distortions caused by IQI.
Compensation schemes and performance analysis of IQ imbalances in OFDM receivers
IEEE Transactions on Signal Processing
IEEE Transactions on Signal Processing
Mathematics Computer Science