The three 802.11 standards share many characteristics. They all use the same
medium access protocol, CSMA/CA, which we’ll discuss shortly. All three use the
same frame structure for their link-layer frames as well. All three standards have the
ability to reduce their transmission rate in order to reach out over greater distances.
And all three standards allow for both “infrastructure mode” and “ad hoc mode,” as
we’ll also shortly discuss. However, as shown in Table 6.1, the three standards have
some major differences at the physical layer.