Performance of OFDM System against Different Cyclic Prefix Lengths on Multipath Fading Channels

Abstract: Orthogonal Frequency Division Multiplexing (OFDM) is a transmission technique that uses several subcarrier frequencies (multicarrier) that are perpendicular to each other (orthogonal). This OFDM modulation technique effectively eliminates Intersymbol Interference (ISI) on a channel caused by the effects of multipath fading. To overcome this weakness, OFDM uses a guard interval (cyclic prefix) inserted in its transmission. This paper analyses the effect of different cyclic prefix lengths on OFDM performance on multipath channels using Matlab. Here, the cyclic prefix length as the main parameter is varied for the different number of subscribers. Meanwhile, Bit Error Rate (BER) and Signal Noise Ratio (SNR) values obtained at the receiver are used to see the system's performance. Based on our simulation results, the best value of BER is obtained using a cyclic prefix length of 1/4 with a Fast Fourier Transform (FFT) size of 512.