Answer 5.12

The symbol energy at the receiver input is given by the signal power x symbol period, thus Eb = 1nW/100 = 1 x 10-11 Watts/Hz. The BER equation for DPSK is:

Pe DPSK = 0.5exp(–Eb/N0) = 0.5exp(–1 x 10-11 / 0.5 x 10-12) = 1.3 x 10-9.