CC2420: how to calculate noise figure in cc2420 transreceiver

i m akhilesh panchal

phd scholar

consider 1% BER then require signal to noise ratio at the receiver is 1000    

path loss =55dB

input tranmitted power =10*10^-6 watt

what is input noise power=? , when noise figure is 8 dB

actually i want to calculate  minimum transmitted power  when  SNR at receiver is 1000 .