Analysis and design of OFDM/OQAM system with hexagonal lattice based on filterbank theory

Wireless channels create both intersymbol interference (ISI) and interchannel interference (ICI) on the transmitted signal. The OFDM-OQAM system with well localized prototype filter can reduce the interference caused due to the transmission over wireless channel, but it is not the optimal choice. In this paper, we propose a new structure for OFDM-OQAM system with hexagonal time-frequency lattice which can minimize the joint ISI/ICI caused due to the transmission channel. Based on this structure, we derive the discrete time model and present the fast implementation for it based on inverse fast Fourier transform (IFFT) by using the polyphase decomposition technique. The conditions for perfect reconstruction are established and in order to optimally combat the impact of propagation channel, an efficient prototype filter is designed. Finally, the computational complexity and the performance of the proposed structure and the conventional OFDM-OQAM system are compared. The results show that our proposed structure outperforms conventional OFDM-OQAM system with a little increase in the computational complexity.