A New Preamble Design for Channel Estimation in Offset QAM Filter Bank Multicarrier Systems

Abstract

In this paper, we propose a new preamble design for channel estimation in filter bank multicarrier (FBMC) systems using offset quadrature amplitude modulation (OQAM). The proposed preamble structure is formed by duplicating a preamble unit (PU) defined as a 3x3 symbol matrix in a time-frequency lattice. The center element of the PU could be a real symbol "1" surrounded appropriately by imaginary symbols "j" and "-j" such that the mean-squared error (MSE) of channel estimation is minimized for the center subcarrier. The center element could also be an imaginary symbol "j" with surrounding symbols set as "1" or "-1" in a similar way for MSE minimization. The proposed preamble design can be regarded as an improved version of the extended interference approximation method with real or imaginary symbols (E-IAM-C) for channel estimation in FBMC/OQAM systems. With the estimated channel gains of all center subcarriers, we can calculate the remaining subcarriers' channel gains simply by linear interpolation. Theoretical analysis and simulation results show that the proposed preamble design for channel estimation outperforms E-IAM-C in terms of the MSE, bit error rate, and computational complexity.