11ac is a 5GHz technology, meaning that the IEEE 802.11ac amendment does not specify its use in the 2.4GHz ISM band. Use of wider channels requires more available frequency space, and the 2.4GHz band is limited to a total of 83.5MHz. Any implementations of the 11ac physical layer specification (PHY) in 2.4GHz are proprietary.
However, 11ac technology isn’t just about the radios. APs are small computers, each having a CPU, RAM, Flash, etc. with each new generation of radio technology, we also get new software features, some of which weigh heavily on the CPU of APs and/or controllers. Some new 11ac dual-radio APs have large CPUs, often dual-core, plenty of RAM, encryption offload, dual Gigabit Ethernet ports, and many other high-end hardware features.
So what makes 11ac so special that it would replace the aging IEEE 802.11n (“11n”)? To answer that question accurately, it’s important to understand that 11ac has been launched in two “waves” (called “Wave-1” and “Wave-2”), based on radio chipset capabilities. The chart below shows a brief difference between the technologies implemented into each of the two Waves.
11ac Wave-1 AP and client device sales have been very successful for the industry, and 802.11ac devices are sure to continue selling well after 11ac Wave-2 devices reaches the market. It takes time for a new line-up of products to be brought to market due to design, manufacturing, and certification. Early 11ac Wave-2 APs will not have DFS certification for some time, and both code stability and feature performance will be unproven.