802.11ac: The Next Wi-Fi Standard

THE UPCOMING 802.11ac wireless networking standard promises to do to 11n what 11n did to 11g. While the IEEE 802.11ac standard probably won’t be completed before the end of 2013 (Draft 2.0 is under development), and although the Wi-Fi Alliance has issued no interoperability criteria, consumer products claiming compliance with 802.11ac could be available on store shelves as soon as the middle of 2012.

Most of these early residential and small-business products likely will spend the vast majority of their useful lives operating backward-compatible to 802.11n. And it’s questionable whether residential users will get much out of 802.11ac, as home Internet connections (to say nothing of residential ethernet switches and router ports) top out well below the 1.3-gigabits-per-second speed that a three-stream, 40MHz 802.11ac product can nominally reach.

The improvements in rate-versus-range performance and overall link reliability even in backward-compatible 802.11n mode should be appealing, however, and video distribution within the home may also provide buyers some incentive to implement 802.11ac early on.

Wi-Fi standards are rated according to their maximum theoretical network bandwidth. Wireless local area networks (WLANs) feature differing levels of performance depending on which Wi-Fi standard they support.

  • 802.11b offers up to 11 Mbps
  • 802.11a and 802.11g WLANs offer up to 54 Mbps
  • 802.11n offers up to 300 Mbps

The performance of Wi-Fi networks in practice never approaches these theoretical maximum. 802.11b networks, for example, generally operate no faster than about 50% of theoretical peak, around 5.5 Mbps.

Likewise, 802.11a and 802.11g networks generally run no faster than 20 Mbps. And even though 802.11n rates at 300 Mbps compared to wired Fast Ethernet at 100 Mbps, the Ethernet connection can often outperform 802.11n Wi-Fi in real-world usage, though some may disagree.

A Wi-Fi network connection operates at the highest possible speed that both endpoints can support. An 802.11g laptop connected to an 802.11n router, for example, will network at the lower speeds of ‘g’.

On home networks, the performance of an Internet connection is often the limiting factor in perceived network speed. Even though files can be shared within the home at speeds of 20 Mbps or more, wireless clients will still connect to the Internet at the speeds supported by Internet providers.

Wi-Fi performance continues to be improved with future generations of the technology. Speeds upwards of 1 Gbps (1000 Mbps) are expected with next-generation 802.11ac Wi-Fi.

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