Comparison of channel estimation techniques for OFDM systems in frequency selective fast fading channels

Channel estimations of many OFDM systems are accomplished by using pilot signals. Two kinds of pilots, frequency-domain pilots and time-domain pilots, are investigated. The performance of these methods in Rayleigh frequency selective channel is simulated. The effects of varying channels on these methods, especially on the time-domain pilot channel estimation technique, are examined. From the results. it can be concluded that when the channel is a slow fading channel time-domain method performs much better than frequency-domain method, but when the channel is a fast fading channel. the performance of time-domain technique is impacted more severely, and is no better than that of frequency-domain technique.