Interchannel interference cancellation in wireless OFDM systems via Gauss-Seidel method

In a mobile fading environment, the time variation of the wireless channels is a dominating factor that leads to the system performance loss. Multipath delay spread also lead to a loss of subchannel orthogonality in orthogonal frequency division multiplexing (OFDM) system, known as interchannel interference (ICI). In this paper, we first analyze the influences of ICI in mobile OFDM system. It is shown that ICI is only a function of the symbol energy (E_s), the subchannel number (N) and the Doppler frequency (f_D) in OFDM system, and is independent of signal constellation. To eliminate ICI, an equalization algorithm based on Gauss-Seidel method is then proposed. The main advantage of the iterative algorithm is to update the data vector x^(k) in each iterative step as soon as the part of the new data vector x^(k+1) have been calculated, therefore, the convergence of the algorithm can be accelerated effectively. The symbol error rate for a 16-QAM system is presented by means of simulation results to confirm the effectiveness of the proposed algorithm.