Performance Analysis of Different Modulations’ Abilities to Combat Multipath Propagation in OFDM Systems

The effects of multipath propagation on the received signal of a basic OFDM system, in which a cyclic prefix is adopted, are discussed and an approximate expression of the received signal in a slow fading channel is given. Some simulation results are provided which show the abilities of PSK, DPSK and QAM modulated OFDM system to combat multipath interference. The effects of signal interference amplitude ratio (SIR) on performance suppressing multipath propagation are also considered. Simulation results indicate that the cyclic prefix is indeed an efficient technique to combat multipath propagation and the SIR is also a remarkable factor for different modulation schemes. Channel estimation can reduce the required SIR greatly for same symbol error probability.