  In this paper my prime objective is to explain the generation of large
tensor-to-scalar ratio from the single field sub-Planckian inflationary
paradigm within Randall Sundrum (RS) single braneworld scenario in a model
independent fashion. By explicit computation I have shown that the effective
field theory prescription of brane inflation within RS single brane setup is
consistent with sub- Planckian excursion of the inflaton field, which will
further generate large value of tensor-to-scalar ratio, provided the energy
density for inflaton degrees of freedom is high enough compared to the brane
tension in high energy regime. Finally, I have mentioned the stringent
theoretical constraint on positive brane tension, cut-off of the quantum
gravity scale and bulk cosmological constant to get sub-Planckian field
excursion along with large tensor-to-scalar ratio as recently observed by
BICEP2 or at least generates the tensor-to-scalar ratio consistent with the
upper bound of Planck (2013 and 2015) data and Planck+BICEP2+Keck Array joint
constraint.
