What is 802.11ac Wi-Fi? Design, Works, Pros & Cons

What is 802.11ac Wi-Fi?

802.11ac Wi-Fi is a wireless networking standard endorsed by the Institute of Electrical and Electronics Engineers (IEEE) that utilizes the 5 GHz frequency band to establish fast and reliable connections for Wireless Local Area Networks (WLANs).

Compared to earlier Wi-Fi standards like 802.11n, 802.11a, b, and g, it delivers significantly enhanced data transfer rates and performance.

Through advanced technologies such as channel bonding, MIMO, and MU MIMO, it can handle multiple data streams, providing data transfer speeds that are at least three times faster than those offered by 802.11n.


  • The working process of the 802.11ac may be almost the same as 802.11n, its predecessor, but its data transfer rate and level of performance is much better.
  • As many as 256 different signals of the same frequency can be squeezed in due to the 256 QAM modulations which help cellular bands.
  • It offers better user experience with varied usage and higher data transfer speed which includes streaming HD videos, file transfer, data backup, and more.
  • The cost as well as antenna support, configuration, and accessibility of spatial streams can be a concern.

Understanding 802.11ac Wi-Fi

Understanding 802.11ac Wi-Fi

The 802.11ac is the approved wireless networking standard by the IEEE or The Institute of Electrical and Electronics Engineers.

This networking standard ensures a high output to the Wireless Local Area Networks or WLANs using the 5 GHz band.

The features included in it is primarily based on the features of its predecessor, 802.11n.

The changes in the design of 802.11ac includes introducing new features such as:

  • Channel bonding to the range of 80 and 160 MHz as compared to 40 MHz maximum of 802.11n, which ensures a 333% increase in speed,
  • MIMO or Multiple-Input and Multiple-Output spatial streams that provides support up to spatial streams as compared to four of 802.11n, thereby resulting in an 100% increase in speed,
  • MU MIMO or Downlink Multi-User MIMO feature of 802.11ac lets using multiple stations with one or more antennae that helps in receiving and transmitting autonomous data streams at the same time,
  • A better and more advanced 256 Quadrature Amplitude Modulation or QAM along with three-fourth and five-sixth optional modes that ensure a 33% increase in speed within short ranges, and
  • Standardized feedback and sounding beamforming that provides super compatibility within the access point and between the connected devices.

All these features included in the 802.11ac have increased the data transfer speed significantly and has also made it more scalable.

This means that the 802.11ac has got all the potential to boost up the throughput notably, and the data transfer speeds by as much as three times in comparison to the 802.11n variant.

There is no doubt that the 802.11ac Wi-Fi will perform at a much faster rate than the 802.11n model, but you should not expect to get a Gigabit of throughput.

This is because the 802.11ac will theoretically be unable to provide more than 1.3 Gigabit per second. Why?

The only reason behind this is that the setting required to reach a speed higher than that will only be available in a high-tech lab and not in your office or home.

It is only a lab setting that will allow three data-streams each running at 433 Megabits per second.

A normal access point will support only eight spatial data streams and the client devices will support only one.

However, it will support streaming several HD-quality videos simultaneously to numerous devices.

Another significant aspect of the 802.11ac, that most of the people do not know, is in its infrastructure. Ideally, the AP will need two Gigabit Ethernet ports, not one.

The frequency band will operate in GHz RF bands only. This will restrict usage. This means that the required wider channel bandwidth by the 802.11ac will be met with.

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The Orthogonal Frequency Division Multiplexing or OFDM helps in modulating the bits while transmitting.

Along with that, the 256 QAM will also upsurge the number of bits from 6 to 8 that are transmitted by each sub-carrier.

This will increase the PHY data rate by 33%.

It is backwards compatible with 802.11n and 802.11a devices, provided they operate in the 5 GHz band. Check out ways to extent wireless network for better signals.

Design and Accomplishments

What is 802.11ac Wi-Fi

One of the most significant accomplishments of the 802.11ac Wi-Fi is that it can perform at a much higher level in comparison to its other counterparts.

With the help of a proportionate Gigabit Ethernet networking, it can deliver:

  • An outwardly instant data transfer and
  • A more straightforward QoE or Quality of Experience.

The primary objective of this Wi-Fi network is to reach out to a larger consumer space using the multiple high definition channels.

The contents are delivered seamlessly to all areas of the network within the house.

On the other hand, at the enterprise level, there seems to be a few significant challenges which include:

  • Working in high-density settings
  • Ensuring higher scores of clients for each AP and
  • Delivering a stable network with lower latencies and top-class speeds.

The design and working process of the 802.11ac Wi-Fi enables it to provide a superb user experience to every client who is served within the AP.

This is true and remains constant even when it has to perform under demanding conditions and deal with heavier workloads.

The efficiency of the 802.11ac is significantly increased by the revolutionary silicon technology. This ensures:

  • A wider bandwidth for the channels
  • A denser constellation and
  • More functionality integrated to the APs.

As per its design, the wireless 802.11ac can operate only in the 5 GHz band.

This is a significant improvement because it eliminates the chances of any interference in the connection and performance at 2.4 GHz.

This, in turn, adds more in the offer list such as:

  • It can be used in Bluetooth headphones and microwave ovens
  • It enables the users to upgrade the hotspot APs and mobile devices to twin band capability
  • This makes the 5 GHz band of the system much more effective and more usable, universally and help the users to streamline their IEEE process and
  • This will be facilitated by the possibilities of any contention between the 802.11 proponents by avoiding it successfully.

As you may know, at 2.4 GHz you will hardly get an 80 MHz bandwidth.

However, the features of the 802.11ac Wi-Fi technology can deal with that challenge. In some situations, it can also send signals at 160 MHz in 80+80 MHz form.

There are also a few other more valuable features of 802.11ac that makes it more efficient.

This includes the choice of a short guard interval that provides a 10% increase in data transfer speed.

In addition to that, the more advanced LDPC or Low-Density Parity Check ensures a much better range and rate by checking and correcting the forward ECC or Error Correcting Codes.

The users can extend the current hardware design of their systems readily because the LDPC codes are premeditated to act like an extension of 802.11n LDPC codes.

It also comes with several usable options such as the STBC or Space Time Block Codes.

These codes are far less in number in comparison to the 802.11n, and there is no redundant beam forming.

This is designed and implemented according to the Wi-Fi Alliance certifications which suggest that the 2×1 mode should be the most basic one.

Therefore, the 802.11ac comes with only these STBC modes:

  • 2×1
  • 4×2
  • 6×3 and
  • 8×4.

This is opposed to the STBC modes in 802.11n which are 2×1 and 4×2 as the basic modes and 3×2 and 4×3 as the extension modes.

However, this variance did not make the 802.11n as beneficial as expected due to the complexities involved in it.

How Does 802.11ac Work? 

The working process of the 802.11ac is somewhat similar to its predecessor, 802.11n, but the performance rate is much better. The new features help in performing different tasks in the following way:

  • It utilizes the eight spatial streams to support wider channels up to 80 MHz and then it combines them with the 160 MHz channels. This means that the spectral bandwidth of the 802.11ac is increased to 8×160 MHz, causing a huge difference in speed and volume of data transfer. It can squeeze in a larger amount of data into the airwaves.
  • The 256 QAM modulation also helps in squeezing 256 different signals of the same frequency. It shifts and twists each into a phase which is marginally different. This helps the network to quadruple the spectral efficiency. This means that the multiplexing technique and wireless protocol will use the available bandwidth and perform better. This is extremely important in cellular bands.
  • The standardized beamforming feature will then transmit the radio signals. This feature will ensure that these signals are directed at a particular device. This will increase the throughput, make it steadier, and, at the same time, reduce the power consumption overall. The physically moving antennae tracks the devices and helps in beamforming. It may also modulate the phase and amplitude of the signals. This leaves an interference free and narrow beam that may be used with one another more effectively.
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The fact that the 802.11ac is backwards compatible helps it to be used for mobile devices as well as routers and work perfectly as desired.

The Pros

1. Different usage

The increase in speed of data transfer will help extensively in streaming multiple and varied media including HD videos. It will also help in data backup, file transfer, and wi-fi network range extension.

2. Employ BYOD programs

Most businesses need a stronger wi-fi coverage to support the different BYOD programs employed by them.

The 802.11ac mobile devices can help in improving the operations and capabilities of these programs significantly by achieving more in a short time.

3. Better user experience

The users will be able to get connected to a larger number of clients with the access point that is supported by 802.11ac.

The features will ensure low-lag gigabit speed that will enhance the speed of email syncing and file downloads.

This will increase the user experience within the bandwidth available for the parallel video streams.

4. Battery life

The fact that the wi-fi interface will exchange data within the access point easily and go back to sleep more quickly will increase the battery life of the device.

5. Sent multiple frames

The MU-MIMO feature will allow sending multiple frames within the access point to several clients at the same time.

This is once again a significant help to the BYOD programs because, in here, most of the devices have only a single antenna.

6. Backwards compatibility

This feature allows more flexibility to the businesses that use a mobile infrastructure. They can use the easily available and extensively used 802.11n access points for a better performance and data transfer speed.

7. Higher speed

Within the 5 GHz spectrum, the 802.11ac can operate at a greater speed using the wider bandwidth. According to a Cisco statement, it can even support devices that need to operate at a speed as high as 3.47 Gbps.

8. Less noise and crowd

There are not too many deployments of 5 GHz Wi-Fi as compared to 2.4 GHz. At least, as of now.

This means that there will be less crowd and noise floor that may interfere with your signals. This means you will have more reliable connections and faster data transfer.

9. Number of channels

You will get to use more channels that will help in a wider subdivision of the spectrum available. This will allow you to isolate your network from others compared to a 2.4 GHz range.

10. Active management

You will be able to manage your network and channels on your router more dynamically using this smarter 802.11ac device.

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Therefore, you will be able to determine the most suitable channel for your specific environment, thanks to the Dynamic Frequency Selection of DFS.

This will also help you to shift a channel to a band that is less congested and is not interfering.

11. Transmitting Power Control

The support to TPC or Transmitting Power Control will help in regulating the power output of the RF transmitter.

This will help in maintaining high-quality and stronger links within the certified limit of power radiation.

This feature will also reduce interference of the signals and overall power consumption.

12. Distance and penetration

Since the 5 GHz signals travel to a shorter distance, these will not penetrate as much as the 2.4 GHz signals. This means that there will be less or no interference with the signals from the neighboring networks.

13. Less connectivity issues

You will have fewer connectivity issues when you use the new 802.11ac WLAN technology. This means that you will need fewer managed service providers or staff, making it more cost-effective.

14. Dual channel

The 802.11ac will support low-powered devices with its dual channel to reduce overcrowding.

This will help in liberation of bandwidth and full utilization of 5 GHz radio. This will simultaneously increase the functionality and data transfer speed.

15. Application performance

The performance of the applications will be much better because the network will support using several applications over several devices. It will also support different operating systems with its enhanced throughput.

16. Edge switching

This will also be improved to reduce the bottleneck on the wireless network. This is a significant benefit for the wireless networks used in schools.

The Cons

17. Dependence

The speed of data transfer and the amount of bandwidth available will largely depend on the guard intervals, and number of spatial streams.

It will also be determined by the ability to support the number of users and Wi-Fi devices, and the distance from the access points as well.

18. Older access points

If you have an older 802.11n client adapter or access point then upgrading it to 802.11ac is not possible.

If you want to do that, you will need to replace the hardware and change all client adapters and access points to make them 802.11ac compliant.

19. The cost factors

This upgrade from 802.11 to 802.11ac involves high cost. This is because the total bandwidth consumption of it will be much higher.

This indicates that you will also need to change the edge switches, the controller, the POE adapters, and even the backbone network.

This cost will be much higher than an 802.11n upgrade cost.

20. Speed and performance

The speed and performance of the 802.11ac will also be varied depending on the configurations, availability of the spatial streams, support for the antennas, and more.

Therefore, if you happen to buy a product with low configuration you may not get larger and combined channel widths.

Wrap up

802.11ac is a Wi-Fi network standard that offers improved connectivity and data transfer speeds compared to its predecessors.

Its design includes features like channel bonding, MIMO spatial streams, and QAM modulation to increase speed and scalability.

Although it may not provide a Gigabit of throughput, it can support several HD-quality videos simultaneously and deliver a more straightforward Quality of Experience.

The 802.11ac Wi-Fi’s design allows it to offer a superb user experience, even under demanding conditions and heavier workloads, with the help of revolutionary silicon technology.

About Puja Chatterjee

Puja ChatterjeePuja Chatterjee is a technical writer with extensive knowledge about computers. She graduated from BIMS. Her expertise includes technology writing and client relationship management gained through over 12 years of experience. Follow Her at Linkedin.

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