What's the expression of the noise for a RF signal?
Yes, you can represent your bandpass noise as:

$ n(t) =n_I(t)\cos(2\pi f_c t)-n_Q(t)\sin(2\pi f_c t),$

where $n_I(t)$ and $n_Q(t)$ represent the inphase and quadrature components of the noise signal. In matlab you can generate this sequence as

n = sqrt(Npwr/2) *(randn(1,len)+j*randn(1,len))


The scaling factor is different than in the baseband case because both the inphase and quadrature components have unit power (before scaling), so when added together the total power is equal to 2 and therefore the $\sqrt{2}$ factor is needed in the scaling factor to get unit power.