TopTechnical Dictionary802.11ac - wireless network standard

802.11ac - wireless network standard

Constantly growing number of wireless devices makes it more and more difficult to use 2.4 GHz band due to wireless congestion - where all the connected devices compete for bandwidth.


WiFi networks in urban areas create a dense network, which combined with a large number of constantly connected devices led to a decrease in wireless connection quality. It is one of the main reasons that wireless IP cameras are rarely used.


2.4 GHz signal can be interfered by other wireless networks, smartphones, tablets, laptops or even microwave ovens operating in the same band. 5 GHz band offers many more wireless channels, which means that even in the presence of other networks operating in the same band, it is easier to avoid mutual interferences.


The quality can further be improved with MIMO technology known from 802.11n standard. 802.11ac standard uses Multi-User MIMO (MU-MIMO) technology which is an improvement over the previous technology and allows to allocate spatial streams to more than one device at the same time. The number of devices depends on the number of antennae and the way MU-MIMO has been implemented, in all cases increasing the bandwidth.


802.11ac standard also provides a new capability of giving the band access to multiple users, coupled with a standard beamforming technology. The main advantage is improved bandwidth of the wireless links.


Table 1. Comparison of wireless network performances



IEEE 802.11n IEEE 802.11ac
single-stream (1x1) 150 Mb/s 433 Mb/s
dual-stream (2x2) 300 Mb/s 867 Mb/s
triple-stream (3x3) 450 Mb/s 1.3 Gb/s

Although the bit rate is one of the most important features defining 802.11ac, a comparison with the most popular 802.11n standard can provide a detailed insight.


Table 2. Comparison of 802.11n and 802.11ac standards


IEEE 802.11n IEEE 802.11ac
up to 4 spatial streams up to 8 spatial streams
3 streams
– maximum bit rate 450 Mbps
3 streams
– maximum bit rate 1300 Mbps
20 and 40 MHz channels 20, 40, 80 and 160 MHz channels
modulation per stream 64-QAM modulation per stream 256-QAM
MIMO Multi-user MIMO
extended frame aggregation
beamforming (beamforming)

Fig. 1. Beamforming (beamforming) in 802.11ac standard


The comparison shows that 802.11ac standard offers more options and improved efficiency. In practice, 802.11ac provides higher bit rates and allows to connect a greater number of devices which can operate at a greater distance from the router.