0E??’8
1.0E??’7
1.0E??’6
1.0E??’5
1.0E??’4
1.0E??’3
1.0E??’2
1.0E??’1
1.0E + 0
??“2 ??“1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Eb/No (dB)
Probability of Bit Error (Pb)
Operating Point A
Operating Point B
FIGURE 2.103 Bit Error Rate (BER) performance of BPSK/QPSK.
PSK: (2.62)
DPSK: (2.63)
Coherent FSK: (2.64)
Noncoherent FSK: (2.65)
All of the above equations are plotted in Fig. 2.104, for sake of comparisons.
Pe
1
2
# e
Eb
2No
Pe Q a?…Eb
No b Pe
1
2
# e
Eb
No
Pe Qa?…2Eb
No b 112 CHAPTER TWO
Theoretical BER Performance Comparison
1.0E ??“6
1.0E??“5
1.0E??“ 4
1.0E ??“3
1.0E??“2
1.0E??“1
1.0E+0
0 2 4 6 8 10 12 14 16
Eb/No (dB)
BER
CD QPSK
CD FSK
NC FSK
DPSK
FIGURE 2.104 BER performance comparisons of binary modulation schemes.
When considering binary signaling, we notice that we pay 3 dB of Eb/No when switching modulation
schemes from PSK to FSK, given the same BER target. Also we see there is a loss of ~1 dB
when using a noncoherent detector compared to a coherent detector. This choice would be made in a
system if a possibly lower-cost receiver was required. It is not the intention of the author to limit the
reader??™s application to highly mobile scenarios, since there are other wireless applications that
deserve attention.
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