Modified Slow Fading Channel Estimation Technique And Fast Fading Channel Estimation Technique For OFDM Systems

Orthogonal Frequency Division Multiplexing (OFDM) is a recent trend which encodes digital data on multiple carrier frequencies. It is widely used in wireless communication systems because of its high data rate transmission power with high bandwidth. Though the channel state changes with time, a transmitted signal will be faded while it will travel through channel. If there is no dominant scatterer present in the medium, the channel response is known as Rayleigh channel else it is known as Rician channel. So, the most crucial part of OFDM system is channel estimation. Our task is to estimate the channel with time and correct the received signal accordingly, so that a receiver can receive the information properly. In this paper, we have implemented two different OFDM channel estimation methods for single carrier systems in which one estimation method is based on fast fading channel or Rician channel and another method is based on the slow fading channel or Rayleigh channel. The Preamble based channel estimation is for slow fading channel in which we have introduced Zadoff Chu sequence as special preamble sequence for estimation. The second method is for fast fading channel which uses pilots for channel estimation. We have introduced a special arrangement of pilots and data to make a OFDM symbol which is able to estimate the channel properly. For both the cases we get a very high signal to noise ratio(SNR) and finally, we made a comparison table between them and made a comparison of our proposed algorithm with the existing algorithm.