Pilot Design with Low Overhead in Spread-Spectrum-Based FBMC/OQAM Systems

Direct sequence spread spectrum technology can improve the bit error rate performance in the application of filter bank based multicarrier system. Aiming at a communication system that combines the spread spectrum technology and the offset quadrature amplitude modulation based filter bank multi-carrier (FBMC/OQAM), this paper proposes a pilot frequency design scheme. The traditional pre-pilot design scheme does not consider the problems of high overhead and low power efficiency, therefore the channel estimation result is inaccurate. The proposed method in this paper combines the symmetry of the spread-spectrum signal and the imaginary interference factor, reduces other overheads except for the pilot, and improves the power of the pilot symbol. The experimental results show that the proposed method has a better bit error rate performance and lower mean square error than the auxiliary pilot method which results in no overhead of additional symbol positions around the pilot. In addition, this study analyzed the spectral efficiency, power efficiency and residual imaginary interference of the pilot design scheme.