Preamble overhead reduction with IAM-C for channel estimation in OQAM-OFDM systems

In this paper, a low overhead preamble structure is proposed for the interference approximation method - complex (IAM-C) method in offset quadrature amplitude modulation based orthogonal frequency division multiplexing (OQAM-OFDM) systems. Compared with the conventional preamble structure with three columns of symbols, the proposed preamble structure only requires two columns of symbols as the preamble overhead. Specifically, 1/3 of the preamble symbols are used as the pilots for channel estimation, the other 1/3 of the preamble symbols are used as the additional data symbols (ADS) for data transmitting and the remaining 1/3 of the preamble symbols are used as the compensating pilot symbols (CPS) for interference eliminating. Furthermore, observing that the power of the transmitted signal is enlarged in existing IAM methods with imaginary pilots, we improve the proposed preamble structure. Simulation results show that the proposed preamble structure can achieve the same channel estimation performance as the IAM-C method. Moreover, the improved preamble structure can achieve better channel estimation performance than the IAM-real (IAM-R) method.