A New Scheme of Pilot Arrangement in OFDM Systems by using a feedback Branch

Channel estimation techniques for Orthogonal Frequency Division Multiplex (OFDM) systems based on a pilot arrangement are investigated. Training based Channel estimation with a block type pilot arrangement is studied through an algorithm for determination of efficient number of pilot symbols in an OFDM symbol by adding a feedback branch. Channel estimation at pilot frequencies is based on Least Square (LS) method while channel interpolation is done using linear interpolation. At the end the influence of the new algorithm on three different Stanford University Interim (SUI) channels are simulated. It will be shown that with this technique a dramatic amount of assigned bandwidth for channel estimation can be saved for data transmission. Also, the Bit Error Rate (BER) performance in the proposed system remains approximately constant in comparison with the state that the maximum numbers of pilot symbols are sent.