The absolute most robust (error-free) settings would be QPSK, rate 1/2 FEC and 1/4 guard interval -- but that might not give you enough Mbps data capacity for what you're doing.
Step one is figure out the data rate you need to transmit. Step two, dial in the most robust parameters that are just enough to meet that data rate. Step three, cross your fingers and hope there is enough signal to noise ratio for the receiver to catch all the data with an extremely low bit error rate.
So if I'm setting up a RF Central Microwave system for a reality TV show and my options are QPSK, 16QAM, or 64QAM. What should I set the transmitter to, to obtain the best quality in the microwave monitor/receiver? And does anyone know about the FEC: 1/2 2/3 3/4 5/6 7/8
Guard interval: 1/32 1/16 1/8 1/4
What are my optimum settings?