The evolution of WiFi standards: a look at 802.11a/b/g/n/ac
When you’re looking to buy new wireless networking gear or a mobile device, you’re faced with an array of choices and abbreviations. Since Wi-Fi was first released to consumers in 1997, its standards have been continually evolving – typically resulting in faster speeds and further coverage. As capabilities are added to the original IEEE 802.11 standard, they become known by their amendment (802.11b, 802.11g, etc.). Here we’ll discuss the basics of each 802.11 Wi-Fi standard.
802.11b uses the same 2.4 GHz frequency as the original 802.11 standard. It supports a maximum theoretical rate of 11 Mbps and has a range up to 150 feet. 802.11b components are cheap, but the standard has the slowest maximum speed of all the 802.11 standards. And since 802.11b operates in the 2.4 GHz, home appliances or other 2.4 GHz Wi-Fi networks can cause interference. Today, routers that only support 802.11n are no longer manufactured.
The ‘a’ amendment to the standard was released at the same time as 802.11b. It introduced a more complex technique, known as OFDM (orthogonal frequency division multiplexing) for generating the wireless signal. 802.11a offers a few advantages over 802.11b: it operates in the less crowded 5 GHz frequency band, making it less prone to interference. And its bandwidth is much higher than 802.11b, with a theoretical max of 54 Mbps.
You probably haven’t encountered many 802.11a devices or routers. This is because 802.11b devices were cheaper and became more popular in the consumer market. 802.11a was mainly used in business applications.
The 802.11g standard uses the same OFDM technology introduced with 802.11a. Like 802.11a, it supports a maximum theoretical rate of 54 Mbps. But like 802.11b, it operates in the crowded 2.4 GHz (and thus is subject to the same interference issues as 802.11b). 802.11g is backward compatible with 802.11b devices: an 802.11b device can connect to an 802.11g access point (but at 802.11b speeds).
With 802.11g, consumers enjoyed a significant advance in Wi-Fi speeds and coverage. At the same time, consumer wireless routers were getting better, with higher power and better coverage than earlier generations.
With the 802.11n standard, Wi-Fi became even faster and more reliable. It supports a maximum theoretical transfer rate of 300 Mbps (and can reach up to 450 Mbps when using three antennae). 802.11n uses MIMO (Multiple Input Multiple Output) where multiple transmitters/receivers operate simultaneously at one or both ends of the link. This provides a significant increase in data without needing a higher bandwidth or transmit power. 802.11n operates in both the 2.4 GHz and 5 GHz bands.
802.11ac supercharges Wi-Fi, with speeds ranging from 433 Mbps all the way up to several Gigabits per second. To achieve this kind of performance, 802.11ac works exclusively in the 5 GHz band, supports up to eight spatial streams (compared with 802.11n’s four streams), doubles the channel width up to 80 MHz, and uses a technology called beamforming. With beamforming, the antennae basically transmit the radio signals so they’re directed at a specific device.
Another significant advancement with 802.11ac is multi-user (MU-MIMO). While MIMO directs multiple streams to a single client, MU-MIMO can direct the spatial streams to multiple clients simultaneously. While MU-MIMO doesn’t increase the speed to any single client, it can increase the overall data throughput of the entire network.
As you can see Wi-Fi performance continues to evolve, with potential speeds and performance nearing wired speeds.