Advantages
 The OFDM transmission scheme has the following key
advantages:
1. OFDM is an efficient way to deal with delay spread in
multipath environment compared with that of a single carrier
system with an equalizer.
2. OFDM is possible to significantly enhance the capacity by
adapting the data rate per subcarrier according to the SNR of
that particular subcarrier.
3. OFDM is robust against narrowband interference since such
interference affects only a small percentage of the subcarriers.
4. OFDM makes single-frequency networks possible, which is
especially attractive for broadcasting applications.
Wireless Communication Technologies 2.5.1
1
Disadvantages
 OFDM also has some drawbacks compared with single carrier
modulation :
1. OFDM is more sensitive to some parameters of the RF circuit,
such as frequency offset, phase noise, I/Q imbalance, etc.
2. OFDM has a relative large peak-to-average power ratio, which
tends to reduce the power efficiency of the RF amplifier.
Pout (dBm)
M=52 OFDM waveform
0.2
OIP3
0.15
IP3
0.1
relative voltage
0.05
0
1 dB
-0.05
Power Amp
(PA)
-0.1
1-dB
compression
point
IM3 output
power
-0.15
-0.2
0
0.5
1
1.5
msec
2
2.5
3
IIP3
Wireless Communication Technologies 2.5.1
Pin (dBm)
2