function [out]=payload_pad_aligned(length,rate);

if(isequal(rate,[0 0 0 0 0]))
     Nibp6s=100;
elseif(isequal(rate,[0 0 0 0 1]))
     Nibp6s=150;
elseif(isequal(rate,[0 0 0 1 0]))
     Nibp6s=200;
elseif(isequal(rate,[0 0 0 1 1]))
     Nibp6s=300;
elseif(isequal(rate,[0 0 1 0 0]))
     Nibp6s=375;
elseif(isequal(rate,[0 0 1 0 1]))
     Nibp6s=600;
elseif(isequal(rate,[0 0 1 1 0]))
     Nibp6s=750;
elseif(isequal(rate,[0 0 1 1 1]))
     Nibp6s=900;
end
Npad=Nibp6s*ceil((length+38)/Nibp6s)-(length+38);
out=Npad;