802.11a was one of the first Wi-Fi communication standards created in the IEEE 802.11 standards family. It is often mentioned in relation to other standards that came later, such as 802.11b/g/n and 802.11ac. Knowing that they're different is useful when buying a new router or connecting new devices to an old network that might not support new tech.
802.11a wireless technology should not be confused with 802.11ac, a much newer and more advanced standard. Getty ImagesThe original IEEE designations have been renamed to avoid confusion among consumers. Although their new designations are unofficial, 802.11b is referred to as Wi-Fi 1, while 802.11a is called Wi-Fi 2. This new naming structure, introduced in 2018, currently extends to Wi-Fi 6, which is the official designation for 802.11ax, the fastest and most recent technology. 802.11a and 802.11b were developed at about the same time. 802.11b enjoyed faster acceptance because its implementation was more affordable. They use different frequencies, so they are incompatible. 802.11a found a niche in businesses, while the less expensive 802.11b became standard in homes. The 802.11a specification was ratified in 1999. At that time, the only other Wi-Fi technology being readied for the market was 802.11b. The original 802.11 did not gain widespread deployment due to its excessively slow speed. 802.11a and the other standards were incompatible, meaning that 802.11a devices couldn't communicate with the other kinds and vice-versa. An 802.11a Wi-Fi network supports a maximum theoretical bandwidth of 54 Mbps, substantially better than the 11 Mbps of 802.11b and on par with what 802.11g would offer a few years later. The performance of 802.11a made it an attractive technology but achieving that level of performance required using relatively expensive hardware. 802.11a gained some adoption in corporate network environments where cost was less of an issue. Meanwhile, 802.11b and early home networking exploded in popularity during the same period. 802.11b and then 802.11g (802.11b/g) networks dominated the industry within a few years. Some manufacturers built devices with both A and G radios integrated so that they could support either standard on so-called a/b/g networks, although these were less common as relatively few A client devices existed. Eventually, 802.11a Wi-Fi phased out of the market in favor of newer wireless standards. U.S. government regulators in the 1980s opened three specific wireless frequency bands for public use: 900 MHz (0.9 GHz), 2.4 GHz, and 5.8 GHz (sometimes called 5 GHz). 900 MHz proved too low of a frequency to be useful for data networking, although cordless phones used it widely. 802.11a transmits wireless spread spectrum radio signals in the 5.8 GHz frequency range. This band was regulated in the U.S. and many countries for a long time, meaning that 802.11a Wi-Fi networks did not have to contend with signal interference from other kinds of transmitting devices. 802.11b networks used frequencies in the often unregulated 2.4 GHz range and were much more susceptible to radio interference from other devices. Although it helps improve network performance and reduce interference, the signal range of 802.11a is limited by the use of 5 GHz frequencies. An 802.11a access point transmitter covers less than one-fourth the area of a comparable 802.11b/g unit. Brick walls and other obstructions affect 802.11a wireless networks to a greater degree than they do comparable 802.11b/g networks.
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Home and business owners looking to buy networking gear face an array of choices. Many products conform to the 802.11a, 802.11b/g/n, and/or 802.11ac wireless standards collectively known as Wi-Fi technologies. Other wireless technologies such as Bluetooth also exist, fulfilling specific networking functions. For quick reference, 801.11ax (Wi-Fi 6) is the most recently approved standard. The protocol was approved in 2019. Just because a standard is approved, however, does not mean it is available to you or that it is the standard you need for your particular situation. Standards are always being updated, much like the way software is updated on a smartphone or on your computer. In 1997, the Institute of Electrical and Electronics Engineers created the first WLAN standard. They called it 802.11 after the name of the group formed to oversee its development. Unfortunately, 802.11 only supported a maximum network bandwidth of 2 Mbps—too slow for most applications. For this reason, ordinary 802.11 wireless products are no longer manufactured. However, an entire family has sprung up from this initial standard. The best way to look at these standards is to consider 802.11 as the foundation, and all other iterations as building blocks upon that foundation that focus on improving both small and large aspects of the technology. Some building blocks are minor touch-ups while others are quite large. The largest changes to wireless standards come when the standards are "rolled up" to include most or all small updates. So, for example, the most recent rollup occurred in December 2016 with 802.11-2016. Since then, however, minor updates are still occurring and, eventually, another large roll-up will encompass them. Below is a brief look at the most recently approved iterations, outlined from newest to oldest. Other iterations, like 802.11be (Wi-Fi 7), are still in the approval process. LifewireBranded as Wi-Fi 6, the 802.11ax standard went live in 2019 and will replace 802.11ac as the de facto wireless standard. Wi-Fi 6 maxes out at 10 Gbps, uses less power, is more reliable in congested environments, and supports better security. Known as the China Millimeter Wave, this standard applies in China and is basically a rebranding of 802.11ad for use in certain areas of the world. The goal is to maintain backward compatibility with 802.11ad. Approved in May 2017, this standard targets lower energy consumption and creates extended-range Wi-Fi networks that can go beyond the reach of a typical 2.4 GHz or 5 GHz networks. It is expected to compete with Bluetooth given its lower power needs. Approved in December 2012, this standard is freakishly fast. However, the client device must be located within 30 feet of the access point.
Keep in mind when distances are mentioned that ranges can be greatly impacted by obstacles that block the signal, so the range mentioned refers to situations where there is absolutely no interference. The generation of Wi-Fi that first signaled popular use, 802.11ac uses dual-band wireless technology, supporting simultaneous connections on both 2.4 GHz and 5 GHz Wi-Fi devices. 802.11ac offers backward compatibility to 802.11a/b/g/n and bandwidth rated up to 1300 Mbps on the 5 GHz band plus up to 450 Mbps on 2.4 GHz. Most home wireless routers are compliant with this standard. 802.11ac is the most expensive to implement; performance improvements only noticeable in high-bandwidth applications 802.11ac is also referred to as Wi-Fi 5. 802.11n (also sometimes known as Wireless N) was designed to improve on 802.11g in the amount of bandwidth it supports, by using several wireless signals and antennas (called MIMO technology) instead of one. Industry standards groups ratified 802.11n in 2009 with specifications providing for up to 600 Mbps of network bandwidth. 802.11n also offers a somewhat better range over earlier Wi-Fi standards due to its increased signal intensity, and it is backward-compatible with 802.11a/b/g gear.
802.11n is also referred to as Wi-Fi 4. In 2002 and 2003, WLAN products supporting a newer standard called 802.11g emerged on the market. 802.11g attempts to combine the best of both 802.11a and 802.11b. 802.11g supports bandwidth up to 54 Mbps, and it uses the 2.4 GHz frequency for greater range. 802.11g is backward compatible with 802.11b, meaning that 802.11g access points will work with 802.11b wireless network adapters and vice versa.
802.11g is also referred to as Wi-Fi 3. While 802.11b was in development, IEEE created a second extension to the original 802.11 standard called 802.11a. Because 802.11b gained in popularity much faster than did 802.11a, some folks believe that 802.11a was created after 802.11b. In fact, 802.11a was created at the same time. Due to its higher cost, 802.11a is usually found on business networks whereas 802.11b better serves the home market. 802.11a supports bandwidth up to 54 Mbps and signals in a regulated frequency spectrum around 5 GHz. This higher frequency compared to 802.11b shortens the range of 802.11a networks. The higher frequency also means 802.11a signals have more difficulty penetrating walls and other obstructions. Because 802.11a and 802.11b use different frequencies, the two technologies are incompatible with each other. Some vendors offer hybrid 802.11a/b network gear, but these products merely implement the two standards side by side (each connected device must use one or the other). 802.11a is also referred to as Wi-Fi 2. IEEE expanded on the original 802.11 standard in July 1999, creating the 802.11b specification. 802.11b supports a theoretical speed up to 11 Mbps. A more realistic bandwidth of 2 Mbps (TCP) and 3 Mbps (UDP) should be expected. 802.11b uses the same unregulated radio signaling frequency (2.4 GHz) as the original 802.11 standard. Vendors often prefer using these frequencies to lower their production costs. Being unregulated, 802.11b gear can incur interference from microwave ovens, cordless phones, and other appliances using the same 2.4 GHz range. However, by installing 802.11b gear a reasonable distance from other appliances, interference can easily be avoided. 802.11b is also referred to as Wi-Fi 1. Aside from these five general-purpose Wi-Fi standards, several other related wireless network technologies offer slightly different value propositions.
The following IEEE 802.11 standards exist or are in development to support the creation of technologies for wireless local area networking:
Additional standards that are not mentioned here may also exist. However, they may have been supplanted or canceled and are not relevant to the information in this article. The Official IEEE 802.11 Working Group Project Timelines page is published by IEEE to indicate the status of each of the networking standards under development.
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