Implementation of an inter-carrier interference self-cancellation technique for OFDM system in Altera CYCLONE II FPGA

Frequency offset is of the main problems in Orthogonal Frequency Division Multiplexing (OFDM) system. A frequency offset between the local oscillator at the transmitter and receiver causes frequency shift in the signal, while in time-varying channel, it can cause a spread of frequency shift known as the Doppler spread. This leads to loss in the orthogonality between subcarriers and results in intercarrier interference (ICI). A simple and effective ICI self-cancellation scheme based on the signal mapper (a, -a) at k, k+1 subcarrier has been proposed to reduce the effect of frequency offset. The aim of this project is to develop the ICI self-cancellation using 64-point FFT/IFFT (IP core from Altera) for practical OFDM transmitter and receiver system. This ICI self-cancellation is designed using VHDL for Altera FPGA device, Cyclone II. Detailed structures of each block in the ICI self-cancellation system are presented.