OFDM has been an attractive choice for digital modulation in the recent years due to its robustness to channel fading and invulnerability to intersymbol interference. However, to achieve an optimal performance the corresponding channel estimation scheme need to be accurate. This book focuses on the use of guard intervals between successive OFDM symbols for channel estimation. A hybrid of blind and semi-blind estimation techniques is proposed to create an energy efficient scheme that can maintain accurate channel estimation as well as a low transmission BER. Multipath fading channel are considered for performance evaluation. The proposed hybrid scheme is tested in static as well as time varying channel environments using computer simulations. Simulation results show that the proposed scheme outperforms the existing schemes on the basis of BER performance for the same SNR.