What is the Wi-Fi 802.11ac standard?

The 802.11ac standard is the most recent iteration of Wi-Fi, as certified by the Wi-Fi Alliance. The most prominent feature of the 802.11ac current standard, is that it is capable of a theoretic maximum speed of 1.3Gbps (166MBps or 1331Mbps). When compared to the current speed of Wi-Fi N, which has a maximum speed of 450Mbps, the 802.11ac current standard is approximately 3 times the maximum speed.

Beamforming

In the real world, 802.11ac will most likely be known for its ability to offer quicker speeds at range. 802.11ac accomplishes this by using the 5GHz frequency, up to 160MHz bandwidth and a technology called Beamforming. Put simply, a router and a device (Phone or Laptop for example) that both contain Beamforming technology will seek one another out. This drastically increases data throughput between the two devices, whilst also lowering power consumption (the transfer will take less time). This differs from 802.11n, as current routers send data in all directions at a given speed, within a type of data bubble. Beamforming will allow a router to detect the exact location of a device and send the data directly to it in a straight line.

To compare speeds, the following test was setup. A Linksys 802.11ac router was tested with a Linksys 802.11n router. The ac router transmitted data at a rate of 30MBps at 2 metres distance and 22MBps, at 13 metres, through two solid walls. The n router could only transmit at 10MBps at 2 metres and 2.31MBps at 13 metres. That’s twice as fast at 2 metres and ten time as quick at 13 metres.

Streams

The data connection between a router and a device is called a stream, with more streams meaning more speed. An 802.11n router has three speeds, 150Mbps, 300Mbps and 450Mbps using 1, 2 or 3 streams respectively. The 802.11ac current standard supports much quicker streams, with a single stream being 450Mbps alone, rising to 900Mbps and 1300Mbps for 2 and 3 streams respectively. Future routers will be able to support up to 4 streams, which will allow up to 3.46Gbps. To achieve the maximum speed, the client device will need to be able to utilise as many streams as the router has.

Bandwidth

The 802.11ac standard also uses 80MHz of bandwidth, compared to 40MHz with n. This increase in bandwidth is how 802.11ac achieves a higher throughput speed. This bandwidth increase does come at a cost, the increase in bandwidth means less channels to use. To minimise interference, 802.11n has three main channels to use, 1, 6 and 11. 802.11ac will only really have 2 channels to use, to minimise interference.

With future devices using 160MHz of bandwidth, 802.11ac can reach speeds of 867Mbps on one stream. This further reduces the amount of available channels to only 1.

Theoretically, with 3 streams at 160MHz, a speed of 2.6Gbps can be reached. In real world tests we won’t be able to reach this speed, but 802.11ac will definitely allow for multiple users to stream HD content simultaneously.