How are IEEE 802.11ac devices able to maintain compatibility with earlier standards that operate in the 2.4 GHz ISM radio bands?

IEEE 802.11ac devices are designed to maintain compatibility with earlier standards, such as 802.11a/b/g/n, which operate in the 2.4 GHz band. While 802.11ac primarily operates in the 5 GHz frequency range to take advantage of its wider channels and higher data rates, it can still support interoperability with devices that operate in the 2.4 GHz ISM band. This compatibility is crucial in environments where older devices are still in use, allowing for seamless integration and connectivity.

The ability to work in both frequency bands makes it easier for users to transition to newer technology while still being able to use their existing devices. This design principle helps to ensure that users can benefit from the improvements brought by 802.11ac without being forced to replace all their legacy equipment immediately. Thus, 802.11ac devices are able to communicate with clients using the earlier 802.11 standards, enhancing overall network flexibility and user experience.