Performance Analysis of OFDM System Over Time-Selective Fading Channels

In fast moving environment, the inter-carrier interference (ICI) due to Doppler spread will degrade the performance of OFDM system severely. Using Jakes´ model for the Doppler power spectrum and linear model for time-varying channel during an OFDM symbol interval, the analytical closed- form expression of ICI power, signal-to-interference ratio (SIR) and signal-to-interference-plus-noise ratio (SINR) are given without assumption on the statistical characteristic of ICI. Moreover, the effect on bit error probability (BEP) performance by the number of concerned interfering subcarriers is analyzed, which helps to choose the number of concerned interfering subcarriers according to the Doppler spread to greatly reduce the complexity of ICI mitigation method with little performance penalty. The simulation results show that the ICI analysis and SIR expression are efficient, and the concerned number of interfering subcarriers should be more with the increase of Doppler spread when ICI mitigation is adopted.