What’s the problem with 2.4GHz?

27 Mar 2017

If you talk to a technical person about Wi-Fi then eventually the subject of 2.4GHz comes up along with a list of issues. The root of this goes back to the early days of Wi-Fi and how wireless spectrum was allocated. Wi-Fi currently operates in two frequency bands – 2.4GHz and 5GHz – however until recently the vast majority of devices and equipment only operated in the 2.4GHz spectrum, this was due to early aspects of licencing and manufacturing which meant a rapid adoption of 2.4GHz and a much slower rate of adoption of 5GHz.

The problem is that the 2.4GHz frequency band is not just used by Wi-Fi, it shares it with Bluetooth, baby monitors, various audio & video senders and pretty much anything else that needs an unlicensed frequency band. It is also the frequency that microwave ovens use and yes that can cause problems in kitchens! The upshot is that the frequency band is overcrowded meaning that Wi-Fi is fighting amongst a lot of wireless noise, generally leading to reduced or intermittent performance.

On top of this the actual spectrum available to Wi-Fi at 2.4GHz is very limited – in theory there are 13 channels but in reality only 3 of these channels are usable without causing interference to other channels which makes it very difficult to design large scale deployments. The situation is so bad on event sites that 2.4GHz can be almost unusable. The good news is that most mobile device manufacturers have increasingly incorporated 5GHz support into their devices over the last few years.

Overall the 5GHz band has a much wider spectrum allocated meaning more channels are available and there is less interference from other devices (although RADAR does use 5GHz, as does some metrological equipment). Today 5GHz is much less crowded than 2.4GHz and provides a much better user experience, however, with the widescale adoption of 5GHz in consumer products such as Mi-Fi units the situation is changing so we may well see increasing problems at 5GHz over time.

Category: Wi-Fi

Comments: 3

  1. Posted by Adrian 29 Nov 2018 at 6:14 PM Reply

    I recently had my broadband provider send an engineer round to solve a problem with difficulties being able to connect to my router on the 2.5Ghz band. It turns out the issue was all my ‘smart’ devices – from Alexa, to smart plugs, to security cameras – around 20 in all. Nowhere near the 255 device limit, but enough to spread the bandwidth so thin than I can rarely connect another device.

    When will ‘smart devices’ be able to use 5Ghz as well? And is this a firmware upgrade or a replacement scenario?

    Also is there a workaround to be able to expand the number of devices that can be attached?

    • Posted by Chris Green 30 Nov 2018 at 4:50 PM Reply

      Many home routers/hubs may have a theoretically high number of simultaneous devices but in reality they can only operate with a small number of devices. It depends on the Wi-Fi standard it supports (802.11b/g/n/ac) and the chipset inside, but the end result is often not enough bandwidth to go around. 5GHz support is generally fixed at the design/build stage due to the chipset and antenna set-up so it is very unlikely that a firmware update can be applied, however, most modern routers/hub now support 2.4GHz and 5GHz simultaneously. Of course the devices connecting also need to support 5GHz and not all do yet. Sometimes those that do will still default to 2.4GHz so you may have to disable 2.4GHz in the device settings to force it to use 5GHz.

  2. Posted by Adrian 30 Nov 2018 at 5:23 PM Reply

    Thanks Chris – you are correct, my router is Dual band and where I can I connect with 5Ghz – phone, iPad, PC etc., It only the Smart plugs, Cameras, Lights etc., that can ONLY use 2.4Ghz. If I want to add a new Smart device I have to turn off some of the others – or reboot the router and just get in quickly!

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