Answer 5.12
The symbol energy at the receiver input is given by the signal power x symbol period, thus
E
b
= 1nW/100 = 1 x 10
-11
Watts/Hz. The BER equation for DPSK is:
P
e
DPSK = 0.5exp(
E
b
/
N
0
) = 0.5exp(1 x 10
-11
/ 0.5 x 10
-12
) = 1.3 x 10
-9
.