We propose a new cyclic postfix based orthogonal frequency division multiplexing (OFDM) system. The proposed system shows superior performance in symbol time synchronization while achieving channel estimation performance comparable to that of conventional cyclic prefix based OFDM system. In the proposed system, an identical postfix is generated at the end of each OFDM symbol by inserting pilot values amongst the data symbols in a frequency domain and performing Inverse Fast Fourier Transform (IFFT) operation on it. Robust time synchronization is achieved by auto- and cross-correlating the postfix. Also, time or frequency domain channel estimation can be realized by using properly designed postfix according to channel estimation method.

A cell search technique utilizing a known postfix for OFDM (orthogonal frequency division multiplexing) cellular systems is described. The known postfix is generated in the time domain by inserting pilots in the frequency domain and plays the role of the cyclic prefix in general OFDM systems. Since it demonstrates good correlation properties, it can be facilitated to synchronize each symbol with an identified postfix. In this paper, two different known postfixes are allocated to each cell. One is used for cell identification and symbol synchronization, which is designed to be different among neighboring cells. The other is used for frame synchronization and is the same for all cells. In the simulation, the cell search is accomplished with a probability greater than 10-3 at -27 dB in a vehicular channel. Even at -30 dB, the cell search probability is greater than 10-2 in a pedestrian channel as well as 10-3 in the AWGN (additive white gaussian noise) channel.