Optimization of guard interval for OFDM performance over fading and AWGN channels using genetic algorithm

Orthogonal frequency division multiplexing (OFDM) is an attractive modulation technique for high data rata wireless local area network (WLAN) because of its good performance in fading channels. In this paper, we employ genetic algorithm (GA) to achieve a minimum degradation of OFDM system over multipath fading and additive white Gaussian noise (AWGN) channels. GA is used to extract the optimum value of the guard interval (GI) parameter, which is introduced to solve the problem of interferences that occur at the receiver. The results show that the optimum value of GI is strongly depends on the maximum delay spread. A series of simulations for the bit error rate (BER) performance as a function of subcarrier L with QPSK as modulation scheme for an optimal GI are presented.