A fast new method to mitigate amplifier-induced ICI in OFDM systems based on predistortion in DFT domain
We consider the problem of inter-carrier interference (ICI) in orthogonal frequency division multiplexing (OFDM) signals stemming from nonlinearities of power amplifiers (PA). OFDM signals often provoke amplifier nonlinearities due to their high peak-to-average power ratio. Predistortion is often considered in order to mitigate the resulting ICI. We consider a digital baseband predistorter based on the memory polynomial model. The predistorter is designed in the frequency domain using the the indirect training and the linear minimum mean-squared error (LMMSE) estimation method. It is shown that the proposed algorithm has a very low computation complexity and is scalable for systems with a large number of subcarriers. The simulation results show that for similar computational complexities, the proposed method has a significant performance improvement in the sense of total degradation compared to the methods in [1] and [2].