Analysis and Compensation of Channel and RF Impairments in MIMO Wireless Communication Systems.

摘要

This dissertation presents analyses and compensation methods of channel andudradio frequency (RF) impairments, including spatially-correlated and keyhole fadingudchannels, impairments in mobile-to-mobile (M-to-M) communications, high-powerudamplifier (HPA) nonlinearity, in-phase and quadrature-phase (I/Q) imbalance andudcrosstalk, both separately and together for multiple-input multiple-output (MIMO)udwireless communication systems.udSpecifically, one cross-layer design scheme is proposed for MIMO systems employingudorthogonal space-time block code (OSTBC) over spatially-correlated and keyholeudNakagami-m fading channels. In addition, the performance of M-to-M MIMO maximaludratio combining (MRC) systems is assessed, over double-correlated Rayleigh-and-udLognormal fading channels. In this regard, a three-dimensional (3D) channel model,udwhich takes into account the effects of fast fading and shadowing, is used to obtainudthe transmit and receive spatial correlation functions.udOn the other hand, we propose a constellation-based and a sequential Monte Carloud(SMC)-based compensation methods for HPA nonlinearity in the case with and withoutudknowledge of the HPA parameters, respectively, for MIMO OSTBC systems. Asudfor the HPA nonlinearity in MIMO transmit beamforming (TB) systems, the optimaludTB scheme with the optimal beamforming weight vector and combining vector is proposed.udMoreover, an alternative suboptimal but much simpler TB scheme, namely,udquantized equal gain transmission (QEGT), is also evaluated in the presence of HPAudnonlinearity. We also propose a compensation algorithm for I/Q imbalance in MIMOudMRC systems, which first employs the least-squares (LS) rule to estimate the coefficientsudof the channel gain matrix, beamforming and combining weight vectors,udand parameters of I/Q imbalance jointly, and then makes use of the received signaludtogether with its conjugation to detect the transmitted signal. Moreover, the performanceudof MIMO MRC in the presence of another RF impairment, namely, crosstalk,udis evaluated.udFinally, a comprehensive compensation method for multiple RF impairments togetherudin MIMO TB systems, is proposed.ud