The 802.11ac WiFi Standard Explained
- News
- 07 Oct, 2020
The most convenient way to access the internet is via wireless networking. The number of people and devices accessing the internet increases year on year. Due to the ever increasing number of connections, many people experience slower seeds and unreliable connections. To improve these issues, a new standard of WiFi has been developed by WiFi Alliance - the 802.11ac standard.
What is 802.11ac?
The 802.11ac standard, also known as WiFi 5 and Gigabit WiFi, is the 5th generation of WiFi. It’s an upgrade from IEEE 802.11n, or WiFi 4. WiFi 5 was designed to deliver improved speeds, WiFi performance, and better range to keep up with the growing number of users, devices, and data bandwidth.
A Short History of the 802.11ac Standard
The goal of WiFi standards (IEEE 802.11) is to improve the wireless local area network (WLAN or Wireless LAN) user experience. New wireless standards are developed to bridge the gaps in the existing standards and to incorporate new technology.
The 4th WiFi generation (IEEE 802.11n) saw a sharp increase in the number of users and devices utilising wireless internet. This resulted in slower speeds and more latency. To improve the 802.11n standard, the Institute of Electrical and Electronic Engineering developed the IEEE 802.11ac standard from 2008 to 2013. The improvements would result in an improved WLAN experience - increased speeds, more bandwidth, and less latency. The updated standard was published in December 2013.
Two waves of products were launched using the 802.11ac standard. The first wave was introduced in 2013 and the second in 2015. The difference between these product waves will be discussed later in this article.
Learn more about the key differences between Internet, Ethernet, WiFi and Cellular technology.
How Fast is the 802.11ac Standard?
Maximum internet speeds are theoretical. They are based on optimum conditions - potential interference is not taken into account. 802.11ac has a theoretical maximum speed of 1,300 Mbps (1.3 Gbps) - 2,300 Mbps (2.3 Gbps). It was the first WiFi standard developed that could theoretically achieve gigabit speeds opposed to megabit speeds. In contrast, 802.11n had a theoretical speed of 450 Mbps (0.45 Gbps). This meant WiFi 5 could be up to 3x faster than the previous WiFi generation under optimum conditions.
In the real-world, data speeds are vunerable to change due to the environment. Obstructions such as building material, windows, doors, walls, and furniture can restrict signal strength, resulting in speed slowdowns.
Forbes states that the fastest real-world 802.11ac speeds recorded are around 720 Mbps (0.72 Gbps). In contrast, the maximum speed recorded for 802.11n was 240 Mbps (0.24 Gbps). While it’s true that WiFi 5 is 3x faster than WiFi 4, the speeds are much lower than the theoretical ones.
802.11ac Key Features
802.11ac built on the features offered by 802.11n to improve throughput, bandwidth, and speed.
Wider WiFi Channels
There are two GHz frequency bands that routers and other wireless devices use to communicate with each other – 2.4 GHz and 5 GHz. Most WiFi devices are dual-band, meaning they use both frequencies to send and receive information. The difference between the two bands is their range, speed, and bandwidth. The 2.4 GHz band provides a greater range but slower speeds. On the other hand, the 5GHz band provides improved speeds but a smaller coverage range.
Within those frequency bands, there are smaller bands that represent WiFi channels. A WiFi channel is what wireless devices use to transmit and receive data. The width (measured in MHz) determines how much data can pass through the channel and at what speed. The traditional channel width is 20 MHz, and channel bonding is used to increase the channel widths. Wider channels tend to be better at transferring data and usually have faster speeds – as long as the channel is not overcrowded and experiencing interference.
To better explain this, think of a channel as a road. Channel bonding is like adding lanes to it, allowing for a greater capacity of vehicles and faster all around speed.
The 802.11n standard only supported 20 MHz and 40 MHz channels (bonds two 20 MHz channels). The first 802.11ac product wave supported a maximum of 80 MHz channel bandwidth. To improve on the first wave, the second wave of products took channel width to a different level. Wave 2 supports up to 160 MHz channel bandwidth. The 160 MHz channel improvement was achieved by bonding adjacent channels or non-adjacent 80 MHz channels (to create the 80+80 MHz channel). As a result, it improved throughput remarkably.
MIMO – Multiple-Input Multiple-Output
MIMO technology uses multiple transmitters and receivers (antennas) to send data to multiple WiFi devices simultaneously.
Originally, 802.11n routers used SU-MIMO (Single-User Multiple-Input Multiple-Output), meaning that the router could only communicate with one connected device at a time. When 802.11ac Wave 1 was launched, there had not been any improvements done to the SU-MIMO technology. Wave 2 products saw significant improvement in its user technology.
Wave 2 802.11ac routers adopted MU-MIMO (Multi-User Multiple-Input Multiple-Output). Routers could now broadcast information to multiple devices at the same time. The new technology only supported downlink (communication from the router to wireless devices) MU-MIMO, meaning they could only transmit data to the client devices simultaneously. The information packets being sent to the wireless router (uplink) could only be sent one by one. This new technology improved speeds and supported more connected devices.
Spatial Streams
All routers and wireless devices have antennas, the number of antennas determines the number of spatial streams (data signals) that can be sent and received at the same time. Spatial streams are represented as 1x1, 2x2, 3x3, 4x4, etc. For example, a 2x2 spatial stream represents two antennas supporting two data streams.
Both 802.11n and 802.11ac devices had this technology, the difference was the number of spatial streams they supported.
WiFi 4 had a maximum of 4 spatial streams and the first wave of WiFi 5 had 3. How does spatial streaming work if they used Single-User MIMO and could only communicate with one client at a time? Mobile devices can support a certain number of streams. Many smartphones only support 1x1 spatial streams, some higher-end smartphones and laptops support 2x2 spatial streams, some computers support 3x3 spatial streams, and there aren’t many devices that support 4x4 spatial streams.
Let's say you have an 802.11n router with three antennas. This router has three spatial streams, and can only allocate them to one device at a time. If an iPhone (1x1) and a Mac (2x2) are requesting information at the same time, they will have to stand in line to receive it. The router will use one of its antennas to talk to the iPhone. After completing communication with the phone, the router will use two of its antennas to talk to the Mac. Multiple spatial streams can be used to communicate with one client at a time, never with multiple devices. Your three-antenna router wasn’t able to make use of its potential due to only being able to interact with one device at a time.
To enhance the communication process and speeds, 802.11ac Wave 2 routers supported 4 spatial streams (later, up to 8). With the improvement of Multi-User MIMO, the clients requesting information did not have to wait in line. The router could allocate one antenna to the iPhone and two to the Mac at the same time. More data could be transmitted and received simultaneously. In addition, since the signal is being allocated more efficiently, power consumption is reduced which improves the battery life on the connected devices.
Beamforming
Before beamforming was used, antennas on routers would transmit signal in all directions. In a way, this was an ineffective use of signal as the signal was transmitted to areas that was not necessary.
Therefore, the wireless signal had less range and was more susceptible to speed slowdowns and interferences. Beamforming is used to improve the wireless signal between the WiFi router and the connected devices. It focuses the signal (known as smart signal) in the direction of the connected devices rather than transmitting it into every direction. Beamforming helps improve the range, speed, and reduce interference.
Beamforming technology existed when 802.11n was developed, but had not yet been standardized. There were numerous different beamforming versions available. In order for beamforming to work, the router and the clients needed to share the same beamforming technology. Unfortunately, with so many beamforming versions, not all WiFi 4 manufacturers implemented the same one.
WiFi 5 standardized explicit beamforming. With the new standards, all manufacturers incorporated the same version. Both waves of WiFi 5 products support what’s called “explicit” beamforming.
More Data Transfer with 256-QAM
Wireless devices use sound frequencies to communicate with each other. When a device transmits data via sound waves, it modulates the frequency of a specific radio channel. The sound wave is made up of bits of binary code (a series of 0s and 1s). The receiving device decodes the sound waves to understand what is being said. This is how all wireless internet data is transferred.
For example, let’s say you open Google. The transmitting signal modulates the frequency of your radio channel to communicate with the router. The router decodes the 0s and 1s to understand your request. After the information is gathered, the same process will send the information to your computer. When your computer decodes the 0s and 1s, the Google homepage will be displayed on your screen. This process is known as quadrature amplitude modulation (QAM).
WiFi 4 used 64-QAM, meaning that devices sending information could only send 6 bits at a time. The QAM technology was improved for WiFi 5. WiFi 5 uses 256-QAM; it allows devices to send 8 bits of binary code at once. This upgrade improved WiFi speeds by 20% - 33%. Both 802.11ac waves supported 256-QAM.
WiFi Frequency Bands
As already discussed, the two frequency bands used to send and receive information are 2.4 GHz and 5 GHz. WiFi 4 supported both frequencies. However, WiFi 5 was developed to only use the 5GHz frequency. This would reduce the amount of interference within the 2.4 GHz frequency. Signal interference is created by numerous devices operating on the same frequency. There is a wide range of devices that operate on the 2.4 GHz band - Bluetooth headsets, microwaves, baby monitors, home phones, etc. All of these overcrowd the band, slowing data. Many of us have experienced this.
In order to use the 2.4 GHz band, WiFi 4 technology had to be incorporated in the development of WiFi 5.
WiFi 5 devices using the 5GHz frequency can take full advantage of all the features offered by the new WiFi upgrade. But, WiFi 5 devices using the 2.4 GHz frequency can only tap into the WiFi 4 technology.
Differences Between 802.11ac Wave 1 and Wave 2
The following chart is an overview of the two types of 802.11ac compatible products:
802.11ac Key Features: |
Wave 1 |
Wave 2 |
WiFi Channel Bandwidth |
20, 40, and 80 MHz |
20, 40, 80, 80+80, 160 MHz |
MIMO |
SU-MIMO |
MU-MIMO |
Spatial Streams |
3 |
4 |
Beamforming |
Explicit Beamforming Only |
Explicit Beamforming Only |
QAM |
256-QAM |
256-QAM |
Frequency Bands |
5 GHz |
5 GHz |
For more information visit Cisco's white paper, 802.11ac: The Fifth Generation of WiFi.
Difference Between 802.11ac and 802.11n
The following chart is an overview of the differences between the 802.11ac and 802.11n standards:
802.11ac Key Features: |
802.11ac |
802.11n |
Theoretical Speed |
1,300-2,300 Mbps |
450 Mbps |
WiFi Channel Bandwidth |
20, 40, 80, 80+80, 160 MHz |
20, 40 MHz |
MIMO |
MU-MIMO |
SU-MIMO |
Spatial Streams |
Up to 8 |
Up to 4 |
Beamforming |
Explicit Beamforming Only |
Many Beamforming Versions |
QAM |
256-QAM |
64-QAM |
Frequency Bands |
5GHz (2.4 GHz with 802.11n technology) |
2.4 GHz and 5 GHz |
Is 802.11ac Backwards Compatible with Older WiFi Generations?
Short answer: Yes.
Backward compatibility is possible due to WiFi 5 using 802.11n technology to tap into the 2.4 GHz frequency. If WiFi 5 devices were only able to use the 5 GHz band, it would not be backward compatible with all previous WiFi technologies.
However, the speed at which the devices operate depends on which WiFi generation they are using. If you have a WiFi 5 computer connected to a WiFi 4 router, the computer can only operate at the speeds achievable by the router. The same thing will happen if you have a WiFi 4 computer connected to a WiFi 5 router.
To make the most of everything WiFi 5 offers, all of the connected devices, and the router will need to have the 802.11ac standard built in.
How Much Area can WiFi 5 Cover?
Total coverage varies based on the frequency band utilised and obstacles (walls, furniture, and building material). The 2.4 GHz frequency is able to travel further and penetrate obstructions better than the 5 GHz frequency. Lifewire states that WiFi routers operating on the 2.4 GHz band can cover up to 45 meter indoors and 90 meter outdoors. Typically, the range will be 3 to 5 meter shorter when using the 5 GHz band.
To increase the range of the router, devices like WiFi extenders and mesh networks have been developed.
WiFi extenders are wireless or wired gadgets that connect to the router and are plugged into a power source to extend the WiFi range. They should be placed in an area that is near enough to the router to get a strong signal, but far away enough to broadcast the signal into the needed areas. After the extender is connected, it’s almost like having two access points. The extender will have its own network name (SSID) and its own password. When you move around your home, you will manually have to reconnect your between your router and the WiFi extender. They tend to work best in small homes or apartments.
Mesh network systems are designed for total home coverage with WiFi. They are made up of multiple mesh nodes that work as one system to extend the WiFi range. One node will be directly connected to the modem using an ethernet cable (fast ethernet or gigabit ethernet), and the other nodes will be positioned around your home. They create one large seamless wireless network. With a mesh network, you will only have one WiFi network name (SSID) and password. As you move around your house, your phone will automatically connect to the node that is closest to it. Mesh systems tend to work best in medium to large homes, offices, and large buildings.
What Devices Support WiFi 5?
It’s been a few years since WiFi 5 was released, and most WiFi devices such as phones, tablets, computers, and router, have the 802.11ac chipsets built into their hardware. You can get wireless-ac routers and clients at your local electronic store, phone store, or directly from the manufactures (Apple, Samsung, Huawei, Netgear, etc).
What Will Come After 802.11ac?
WiFi standards are constantly evolving to improve the WLAN experience for all IoT (internet of things) devices. 802.11ax, or WiFi 6, is the next generation of WiFi. It builds on, and improves, the WiFi technology WiFi 5 offers - faster wireless speeds, higher throughput, lower latency, and more bandwidth.
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We’re here to assist with any issues you might be experiencing with poor cell service. Contact us today, or call us at 011 749 3085.