In the Orthogonal Frequency Division Multiplexing (OFDM) systems, where the data symbols are
transmitted in parallel on different carriers, the length of a symbol is extended. This extension of the
symbol length causes the OFDM system to be less sensitive to channel dispersion than a single
carrier system transmitting data symbols at the same data rate. However, at the edges of the OFDM
symbol, the channel dispersion still causes distortion, and hence introduces interference between
successive symbols (i.e. Inter-Symbol Interference, ISI) and interference between different carriers
within the same symbol (i.e. Inter-Carrier Interference, ICI). Different guard interval techniques for
the OFDM transmission were suggested to reduce the interference between successive symbols. The
most commonly used guard interval is the cyclic prefix (CP). In this paper, the impact of replacing
the CP by zero insertion (ZI) before the Inverse Fast Fourier Transform (IFFT) process on the
OFDM transmitter is studied. The motivation of using the ZI instead of the CP is the reduction in
the transmission rate and the high performance in reducing the channel distortion. Moreover, the
proposed ZI-OFDM system is suitable to minimize the effect of the fading channel when the
channel characteristics are unknown or difficult to be estimated. Another approach to enhance the
OFDM system is also introduced in this paper. A signal denoising approach is suggested to be
added in the receiver to reduce the effect of the additive white Gaussian noise (AWGN) channel. In
this approach, the Radio Frequency signal (RF) is enhanced using a wavelet thresholding technique
instead of enhancing the baseband signal. The simulation results show that the proposed ZI
approach provides better transmission performance than the recent techniques and achieves a 20 %
reduction in the data redundancy relative to the redundancy in the CP-OFDM system. Moreover, the
results show that the proposed thresholding approach significantly removed the noise and the signal
power is enhanced by almost 30 db with different values of the channel signal-to-noise ratio (SNR).
The overall system performance of the proposed ZI approach in the transmitter together with the
thresholding approach in the receiver is tested in this paper.