A new CAZAC-based preamble for OFDM systems

Digital Video Broadcasting - Second Generation Terrestrial (DVB-T2) is a new standard used for the digital terrestrial television broadcast. Compared with the first generation DVB-T, it introduced various advanced technologies to improve system capacity and transmission reliability. One of the new designs in DVB-T2 is to use P1 symbol as the preamble to help the receiver to achieve fast synchronization. Although lots of research work has been done to improve the synchronization performance by P1 symbol, many disadvantages (such as high complexity to generate P1, little information carried by P1 symbol, weakness in carrier frequency offset estimation under multipath channels, etc.) remain. Based on constant amplitude zero auto correlation (CAZAC) sequence, a new preamble denoted as C1 is therefore proposed in this paper for the synchronization of orthogonal frequency division multiplexing (OFDM) systems. In the proposed scheme, the coarse timing synchronization and fractional frequency offset (FFO)estimation are done simultaneously in the time domain, while the integral frequency offset (IFO) estimation and the transmission parameter signaling (TPS) decoding are done in the frequency domain. Analysis and simulation results show that, compared with P1, the proposed preamble C1 not only has a lower implementation complexity and a lower peak to average power ratio (PAPR), but also can carry more system information for the receiving demodulator. The synchronization scheme with C1 performs better than that with P1 in timing and frequency offsets estimations under multipath channels. Therefore we conclude that the proposed preamble is more suitable for wideband OFDM systems under multipath environments.