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Suffering From Wi-Fi Congestion? Dual 5GHz Radios Can Help

By Keith Mcintyre in · Technology · July 20, 2016

Let me put this to you: You have multiple access points in your network and you’re experiencing performance issues on the 2.4GHz frequency band. If I could give you the option of switching your older 2.4GHz radio in your current access point to a newer 5GHz radio, would you do it?

WLAN (Wireless LAN) engineers know that a good dual-band Wi-Fi design will have some 2.4GHz radios turned off in some access points to reduce interference. Whilst it is good design to turn off some 2.4GHz radios, by doing so, that lovely access point you’ve paid $800 for is effectively only using half of its functionality. Maybe it would have been better to pay $400 if you’re only using half of the access point?

So… we know it’s good design to turn off some 2.4GHz radios in your access points, but in doing so, I’m only using half of the access point. What can I do?!

In this article I’m going to address the issues experienced with the 2.4GHz frequency band and explain the solution to help you achieve better network performance and superior Wi-Fi design. 

2.4GHz – The Legacy Band 

For over 10 years, the 2.4GHz band has been extensively used across all Wireless LANs. It’s no secret that this has helped drive the success of Wi-Fi globally. However, that success has also been the 2.4GHz downfall.

The Wi-Fi boom saw a huge shift in technological devices that were able to connect to a wireless network. Most of these devices were connecting to the network on the 2.4GHz frequency band, but they weren’t the only devices using this frequency. Microwave ovens, baby monitors, electronic garage doors, and Bluetooth devices are just a few examples of devices that also operate on the 2.4GHz band. This boom in devices resulted in severe congestion on the network.

The 2.4GHz band only has 3 non-overlapping channels (typically used in a 1, 6 and 11 configuration), so it was always going to be limited in capacity. "What on earth is a non-overlapping channel?" This is probably what some of you are thinking. Well, this is where the techy bit comes in.

The channels on the 2.4GHz spectrum are 20MHz wide, with each one separated by 5MHz. The entire 2.4GHz spectrum is around 100MHz wide and has 11 selectable channels within it. Ultimately fitting this many channels into such small space means that some of the channels end up overlapping with each other. This is what we call adjacent-channel interference in Wi-Fi. 

Most households, offices, bars, restaurants and even some cars offer the ability to connect to a wireless network. With so many wireless networks around, it’s virtually impossible to have a completely clean 2.4GHz spectrum. The end result is a congested frequency band with limited scalability.

5GHz – The present and future

We know the 2.4GHz band has 3 non overlapping channels, but what about 5GHz? Well, 5GHz is a wider spectrum and as a result has 25 non overlapping channels (in the USA).

For the last ten years, most devices that are Wi-Fi enabled have been solely 2.4GHz compatible. It’s only been the last two to three years where we’ve started seeing everyday devices manufactured and shipped with 5GHz capabilities. 

One of the biggest benefits of 5GHz is that it provides the foundation for the newest Wi-Fi standard: 802.11ac. This standard offers denser modulation schemes, wider channels, more spatial streams (up to 8x8 with the relevant hardware) and more, which is why it’s faster than older Wi-Fi standards like 802.11n. It’s worth pointing out that whilst 802.11ac is backwards compatible with older Wi-Fi standards, it is 5GHz-only, and as a result cannot be used on the 2.4GHz band.

2.4GHz vs 5GHz

Let’s take a comparative look at the two frequencies or ‘bands’ that we currently use in Wi-Fi. You’ve heard the numbers 2.4 and 5 mentioned numerous times throughout this article, these are the frequency bands that we use to connect clients to a wireless network. 

 

  • Range – One of the main differences between the two bands is the propagation properties of the signal (how far your data can travel). 2.4GHz has a longer range then 5GHz due to the fact 2.4GHz is a lower frequency. Higher frequencies are absorbed by environmental objects like walls and doors more than lower frequencies. Thus 2.4GHz range is further than 5GHz. For a more comprehensive overview of ‘What is the range of Wi-Fi’ click here.
  • Interference – Interference in Wi-Fi is incredibly common. The more interference there is on a given frequency, the worse your network will perform. Microwave ovens, cordless phones, and baby monitors are all common sources of interference on the 2.4GHz frequency band. The 5GHz frequency band sees a lot less interference than the lower 2.4GHz frequency band.
  • Speed – The 5GHz frequency band allows for higher data rates compared with 2.4GHz. For a more comprehensive overview on ‘what is the real speed of Wi-Fi’ click here.
  • Channels – Wireless communications are transmitted on specific frequencies. These are known as channels. In the 2.4GHz band there are only 3 non-overlapping channels 1, 6 and 11, whereas the 5GHz band has 25 non overlapping channels! (in the US)

Software Selectable Dual 5GHz Radios

Now we can talk about the really cool technology: software selectable Dual 5GHz radios in an access Point. We’ve already discussed that the 2.4GHz frequency band has limited capacity, and how it’s overcrowded and is limited in speed. And how the 5GHz frequency band is bigger and faster.

We also know that most access points shipped around the world are dual band, which means they have one 2.4GHz and one 5GHz radio within them. With a software selectable dual 5GHz band access point, you have the ability to switch the 2.4GHz radio into a second 5GHz radio. So, instead of being a dual band 2.4GHz and 5GHz access point, you now have a single band, dual 5GHz access Point. This technology allows for flexibility, better network efficiency, and optimal Wi-Fi design.  

 




So, why would I want a software selectable dual 5GHz band access point?

ROI (Return on investment) – One of the key benefits of a software selectable dual 5GHz radio access point is ROI. For example, in many schools, the typical Wi-Fi deployment is one access point per classroom to account for the High Density nature of the client load. As a result, many WLAN Administrators end up turning off 2.4GHz radios on various neighboring access points to prevent CCI (co-channel interference). 

Whilst turning off some 2.4GHz radios on your access points may improve network performance, it actually means you’re only using half of the Access Point that you have invested in.

With a software selectable dual 5GHz access point you can switch the 2.4GHz radios that would normally be switched off to prevent CCI to be a second 5GHz radio. This allows for greater client capacity and allows you to continue using the full potential of the access Point.

High Density EnvironmentsHigh Density (HD) or Very High Density (VHD) are areas where clients are connecting to the WLAN within a small confined space. An example of a VHD or HD environment can be an auditorium, gymnasium, or cafeteria. 

Due to the large number of clients wanting to connect to the WLAN, more access points than usual will be needed. More clients connecting to the WLAN, generally means more bandwidth will be required which is not scalable on the 2.4GHz band.

Another factor to consider in HD/VHD environments is the type of applications that will be used. Many VOIP applications like Skype and GoToMeeting can be bandwidth intensive, and as a result they may encounter latency or jitter problems when connected on the 2.4GHz band. 

This situation also applies when watching HD videos via Netflix of YouTube. You may experience severe buffering or a complete loss of video altogether. Switching to software selectable dual 5GHz can alleviate these problems when operating in a HD/VHD environment.

Manufacturing Environments – Most manufacturing environments have an incredible amount of 2.4GHz interference due to the challenging nature of Radio Frequency (RF).

Multipath can be a huge problem in a manufacturing environment. Multipath occurs when the transmitted signal reflects off various environmental objects, causing multiple copies of the same signal to arrive at the receiver. In 802.11a/b and g clients, multipath causes data corruption. Multipath with 802.11 n/ac clients is actually good because the antennae can receive out of phase signals and put them back in the correct order.

Reflection, absorption, and signal scattering are all common issues experienced alongside multipath in this kind of environment. Many of the clients connecting to the WLAN are only 2.4GHz compatible it’s imperative that the 2.4GHz band is functioning as well as it can. 

In manufacturing/warehousing environments where metal shelving is common, having the flexibility to switch the 2.4GHz radio to a second 5GHz radio can improve client performance and simplify the deployment.

Multi-Tennant Buildings – Imagine you’re in an office working on the 5th floor of a multi-tenant building. How much 2.4GHz signal bleed over can you expect?

It’s incredibly common for office workers to experience client connectivity problems on the 2.4GHz band. This stems not only from neighboring access points to the left or right of your office. But also from neighboring access points located above and below your office (this is known as signal bleed over). Adding other devices like microwave ovens, CCTV cameras and Bluetooth devices into the mix just adds further strain to an already over-utilized band.

Switching to a software configurable 5GHz radio can allow client devices that are 5GHz compatible to connect to a clearer, less contended band. This will significantly help with client performance.

In conclusion, the 2.4GHz frequency band is overcrowded and limited in capacity. The 5GHz frequency spectrum is bigger, less congested, and allows for higher data rates. Having the ability to change the 2.4GHz radio in your access point to a second 5GHz radio can reap huge benefits on network performance. 

This dual band (software selectable to dual 5GHz) 802.11ac access point is a great place to start reaping those benefits. And if you want to try it out, you can do that here.

For More Information:

Designing WLANS: What If We Could Double Our Airtime At 5GHz?

Suffering From Wi-Fi Congestion? Dual 5GHz Radios Can Help

Is 2.4GHz Dying? Or Is It Already Dead?

Keith Mcintyre (@keith_mcintyre)

Keith McIntyre is an Inside Systems Engineer at Aerohive Networks. Keith has a background in wireless technology including pre-sales engagement, network planning, RF design, installations and troubleshooting with multi-vendor products.