For high data rate communication with the required Quality of Service (QoS) in 3G and 4G systems, Orthogonal Frequency Division Multiplexing (OFDM) is proposed, which is capable to resist the channel impairments caused by high mobility conditions, by dividing the frequency-selective fading channel into narrowband flat fading channels. For increased data rate and reduced latency for 4G radio communication standards, ITU made proposals for LTE-Advanced in 2009. To achieve Release-10 targets, made by 3rd Generation Partnership Project (3GPP), channel state information at the transmitter is a pre-requisite. This book focuses on channel estimation algorithms in three domains: Frequency Domain Channel Estimation, Time Domain Channel Estimation and Adaptive Filtering Based Channel Estimation.