For coherently demodulated BPSK what should EbN0 be in dB so

For coherently demodulated BPSK, what should Eb/N0 be in dB so as to give a bit error probability of 0.0015? Choose the closest answer. A: 3.5 dB. B: 7.5 dB. C: 6.5 dB. D: 4.5 dB. E: 5.5 dB

Solution

Pe= probability of error= 0.5*erfc(E/no)

Given Pe= 0.0015

Hence. erfc(E/no)= 0.003

Using table: E/no= 2.09

E/no=6.4 db

(C) 6.5 db is correct