[en] The heavy-ion fusion at sub-barrier energies continue to be an outstanding issue of broad experimental and theoretical interest for the community and is particularly complex due to the interplay of couplings of inelastic excitations and transfer channels. To study the transition of nuclear reactions from well above to deep sub-barrier energies, the fusion excitation functions for different systems have been measured for a wide energy range around the Coulomb barrier energies and interpreted in the framework of coupled-channels approach. The findings of the measurements conclusively demonstrate the phenomenon of fusion hindrance at deep sub-barrier energies in both positive and negative Q-value systems and the strong dependence of couplings of inelastic excitations and transfer channels. In this talk, the behavior of sub-barrier fusion in terms of couplings of inelastic excitations and positive Q-value neutron transfer channels will be discussed