Varying modulation schemes Recalling once again, SDR systems
must inherently accommodate a variety of modulation schemes that
vary in their demands and complexity within the same system
architecture. Higher-order schemes, such as 64QAM, are employed
when signal conditions permit in order to deliver higher data
rates. To show the effect of using such modulation techniques,
the 16QAM source in the previous example is replaced with a
64QAM source of the same bandwidth and pulse shaping. The
software automatically configures the receiver to detect the
64QAM signal. Figure 4 shows the resulting BER simulation with
phase noise using 64QAM with the same receiver RF
characteristics described in Figure 6. The best achievable BER
using 64QAM is 10-3. BER evaluation of the receiver when
presented with a 64QAM signal including the effect of phase
noise. 64QAM receiver performance excluding the effect of phase
noise. The CCDF of both 16QAM and 64QAM signals. The 64QAM BER
results are shown in Figure 5 (with phase noise re