This book discusses the basics of an Orthogonal Frequency Division Multiplexing (OFDM) System and the several radio impairments effects to its Bit Error Rate (BER) performance. Graphical representation of Scatter plot and BER plot for different modulation Schemes, coding schemes and code rates are shown here to analyze the performance of OFDM system. The effects of different Cyclic Prefixes, Pilot channels and Inter-leaver on OFDM system are also observed. Peak-to-Average Power Ratio (PAPR) which is one of the major drawbacks of OFDM system is also discussed here along with the discussion of different PAPR reduction techniques. Finally, a new technique called “Double Companding” by means of multiple companding has been proposed to reduce the PAPR. The simulation results show that it has better performance in terms of PAPR reduction than the conventional companding scheme.