Digital Baseband Compensation for Mobile SFBC-OFDM Systems with Receiver I/Q Imbalance

Abstract

Abstract-In-phase and Quadrature-phase (I/Q) imbalance is a major performance-limiting impairment for directconversion Orthogonal Frequency Division Multiplexing (OFDM) transceivers. I/Q imbalance degrades the Signal-to-Noise-Ratio in an OFDM system by causing Inter-Channel-Interference (ICI) between image subcarriers. Doppler spread due to mobility also causes ICI but mainly between adjacent subcarriers. In this work, we investigate the combined effects of mobility and I/Q imbalance in a Multiple-Input-Multiple-Output-OFDM system with the Alamouti Space-Frequency Block-Coding scheme and design an effective compensation technique. Furthermore, we propose a novel pilot allocation and channel estimation scheme, and exploit the problem structure to reduce complexity.

Digital baseband compensation of joint TX/RX frequency-dependent I/Q imbalance in mobile MIMO-OFDM transceivers

“…Again, it is evident from the simulations that our proposed digital baseband compensation scheme results in substantial performance improvements. We conclude by mentioning that we also developed estimation and compensation schemes for MIMO-OFDM transceivers that use space-frequency block coding (SFBC) to achieve diversity gains (see [11] for more details). VII.…”