For certification test, it is necessary to set different modulation types and bit rates for certain test items. UniTest Tool does not allow you to "directly" set modulation types. However, the modulation type can be “indirectly” selected by [Data rate]:
802.11b bit rates:
1 Mbps uses DSSS with CCK coding and DBPSK modulation,
2/5.5/11 Mbps use DSSS with CCK coding and DQPSK modulation
802.11g bit rates:
6/9 Mbps use OFDM with BPSK modulation,
12/18 Mbps use OFDM with QPSK modulation,
24/36 Mbps use OFDM with 16-QAM modulation, and
48/54 Mbps use OFDM with 64-QAM.
802.11n bit rates:
6.5 Mbps use OFDM with BPSK modulation,
13/19.5 Mbps use OFDM with QPSK modulation,
26/39 Mbps use OFDM with 16-QAM modulation, and
52/58.5/65 Mbps use OFDM with 64-QAM.
7.2 Mbps use OFDM with BPSK modulation,
14.4/21.7 Mbps use OFDM with QPSK modulation,
28.9/43.3 Mbps use OFDM with 16-QAM modulation, and
57.8/65/72.2 Mbps use OFDM with 64-QAM.
A certification agent should, in theory, test through all the various modulation schemes. However, it is quite time consumption and costly to do so. In practice, it is usually good enough and perfectly fine to just measure with 1 Mbps and 72 Mbps.
1 Mbps will in general have the highest harmonic emission content of all the various bit rates, while the 72 Mbps, having the most information stuffed into the same bandwidth, will have the highest intermodulation products, visible in the band edge measurements (the transmission spectrum will have "shoulders").
We have been assured by an expert from a certification lab that measuring those two bit rates is sufficient.