Channel estimation algorithms explain the behavior of the channel and its allow the receiver to approximate the impulse response of the channel. This knowledge of the channel's behavior is well-utilized in modern radio communications. Adaptive channel equalizers utilize channel estimates to overcome the effects of noise.Once a model has been established, its parameters need to be continuously updated(estimated) in order to minimize the error as the channel changes. If the receiver has a prior knowledge of the information being sent over the channel, it can utilize this knowledge to obtain an accurate estimate of the impulse response of the channel. This method is simply called Training sequence based Channel estimation. It is easy to use in any radio communications system.