Broadband Communications In The Memory Of Rf Power Amplifier Modeling Technology

Since the number of users and broadband communication traffic rise rapidly, radio frequency resources are becoming more and scarcer. To enhance spectrum efficiency,linear modulation and multicarrier techniques are widely adopted in modem wireless communication systems . Their non-constant envelope signals require to be amplified linearly. However,in order to increase power efficiency,Pas are often driven into the saturation region,where nonlinear distortion is severe. Linearization techniques play a key role to resolve the conflict between efficiency and power efficiency.Predistortion is a promising technique to linearize power amplifiers. Its effect heavily depends on the corresponding PA model. In broadband communication systems,such as WCDMA and OFDM,the memory effects can no longer be ignored and the performance of traditional memory less modeling and predistortion method is seriously degraded.In this paper,methodologies of nonlinear systems are applied to model and predistort power amplifiers with memory effects in broadband communication systems. Mainly including:The main nonlinear characteristics of power amplifiers and the basic modeling theory are describedMethods of analyzing memory effects of PAs are proposed. After investigating the Phenomena and the causes of PA memory effects,methods based on Hammerstein model are proposed to analyze the dynamic PA characteristic curves.After analyzing the characteristic of the Volterra series, a new pruned Volterra series is proposed.The proposed approach utilizes the complex QR-decomposition based recursive least squares (QRD-RLS) algorithm, which is implemented using the complex Givens rotations, instead of the standard least squares algorithms to updating the coefficient vector of the memory polynomial modeling. The performance of the proposed method is validated through computer simulations.