Sensitivity = -174dBm/Hz + 10*log(BW) + NF + SNR
where, NF is the receiver chain noise figure, SNR is coresponding to the modulation type and BER specification.
for every digital modulation scheme there is BER curve
this curve relate the SNR to the BER , by knowing the BER u can get the SNR required by the demodulator.
that's it