Timing and frequency synchronization in OFDM systems using the cyclic prefix

We present a method for the joint estimation of timing and carrier-frequency offset in Orthogonal frequency-division multiplexing (OFDM) systems. We show that it is possible to generate these estimates without the use of pilots, by exploiting the cyclic prefix of OFDM frames. We derive the joint likelihood function of the offset-parameters given the received data. The performance of the resulting method can be improved considerably by averaging several likelihood functions before the peak detection. Simulations show that even without pilots the frequency estimator is capable of operating in a tracking mode and the timing estimation can be used in an acquisition mode.Godkänd; 1995; 20080220 (ysko)