  The effect of inelastic excitation of exotic light projectiles (proton- as
well as neutron-rich) $^{17}$F and $^{11}$Be on fusion with heavy target has
been studied at near-barrier energies. The calculations have been performed in
the coupled channels approach where, in addition to the normal coupling of the
ground state of the projectile to the continuum, inelastic excitation of the
projectile to the bound excited state and its coupling to the continuum have
also been taken into consideration. The inclusion of these additional couplings
has been found to have significant effect on the fusion excitation function of
neutron-rich $^{11}$Be on $^{208}$Pb whereas the effect has been observed to be
nominal for the case of proton-rich $^{17}$F on the same target. The pronounced
effect of the channel coupling on the fusion process in case of $^{11}$Be is
attributed to its well-developed halo structure.
