| The basic principle of OFDM is to split a high rate data stream into a number of lower rate streams that are transmitted simultaneously over a number of sub carriers. The benefits of OFDM are lower multi-path distortion, resiliency to inter symbol interference and high spectral efficiency.One of the most important characteristics of wireless communication is multipath transmition. Multipath transmition results in signals overlapping each other, and brings to Intersymbol Interference (ISI). The Orthogonal Frequency Division Multiplexing (OFDM) technique divides the frequency spectrum available into many independent sub-carriers. The sub-carriers keep orthogonal to one another and the spectrum overlap. It increases the spectral usage efficiency, and at the same time, it can reduce ISI greatly. The OFDM technique is applicable to high-speed data transfer in environment of multipath and frequency selectivity channel.OFDM system faces a major problem is the sensitivity of frequency offset. Frequency Offset will lead to the ICI. It greatly reduces system performance. This article analysis the ICI caused by the frequency offset, ICI is also curbed by the three methods: SC, MLE and EKF for the simulation and performance ratio more. |
