Research On ICI Equalization Of OFDM-CP System Based On LMMSE Algorithms

Equalization techniques play important roles in modern wireless communication systems.For single carrier systems, the inter symbol interference equalization method, which can resist frequency selective fading channel, has attracted extensive research work. For OFDM systems,the multi-path interference can be suppressed by its inherent characteristics. Recently, a variety of equalization methods have been proposed to mitigate frequency-time selective fading channel for OFDM systems.Firstly, we introduce the basic knowledge of ICI equalization for OFDM systems over time-varying multi-path channels,including a method about how to quickly get the frequency domain channel metrix using FFT, the derivation process of ICI power distribution and matched-filter bound, also the traditional ICI equalization algorithms.This thesis focused on reduced-complexity equalizers. The traditional equalizers have a prohibitive complexity, which leads researchers to paying more efforts to the suboptimum but low-complexity equalizer. In this paper we study several low-complexity equalization algorithms, including recursive linear MMSE equalizer and another equalizer based on matrix decomposition. Based on this,we propose a partial MMSE equalizer,which can achieve a compromise of performance and complexity for the relatively low computational complexity and implementing easily to project implementation.