Since wifi released in 1997.It’s standrad is continully evolving,results in speed 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-1999-11Mbps
802.11b uses 2.4GHz same as original 802.11 standard. It reach the maximum speed upto 11Mbps and coverage upto 150 feet.802.11b components are cheap. 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.
802.11a-1999-54Mbps
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.
802.11g-2003-53Mbps
802.11g uses same OFDM(orthogonal frequency division muiltiplexing).
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.
802.11g uses same OFDM(orthogonal frequency division muiltiplexing).
802.11n (Wi-Fi 4)-2009-450Mbps
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 (Wi-Fi 5)-2014-1GBps
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.