I am not sure why major telecommunications companies such as Ericsson and Qualcomm employ engineers with multiple degrees and years of experience. They only have to visit some of the barbeques that I attend and you find the real ‘experts’ in relation to 5G and electromagnetic radiation.

I want to arm my readers with some data to help at their next local BBQ.

5G is fantastic. It promises higher speeds with lower latency and the ability to support more devices in a given area. But, as Shakespeare said in the Merchant of Venice, all that glisters is not gold. You don’t often hear conversations about reception in relation to 5G. As much as 5G is fantastic from a performance point of view, the range of 5G is less than that of 4G or 3G.

To explain, I need to go back to the beginning.

Radio waves are part of the electromagnetic spectrum. Frequencies range from 3kHz (kilohertz) to 300GHz (gigahertz). To send data on a radio wave you are relying on the peaks and troughs of the sine wave to represent a one or a zero. For a computer, these ‘bits’ of data are the basic building blocks. Put eight of these ‘bits’ of data together and you have a byte. For example the letter T is 01010100 in binary.

For a radio wave, one full cycle can represent a one or a zero. One cycle is defined as one hertz (Hz). So eight cycles could represent one byte of data. As radio progressed, various encoding techniques allowed approximately three bits of data per cycle. With mobile phones, the current lowest frequency we use is 700MHz. At that frequency, we have a theoretical data transmission speed of 2.1 gigabits per second (Gbps) or 262.5 megabytes per second (MBps). Theoretically.

As you move to higher frequencies, you can potentially increase the speed of 4G. So increase that 700MHz to 1800MHz or 2600MHz for example and you could theoretically see speeds of 7.8Gbps – but various overheads in the transmission process and other factors limit the speed to a theoretical maximum of 1Gbps and real-world speeds much less than this.

One way that 5G delivers its promised benefits is with higher frequencies. In Australia 5G is typically using 2.6GHz and 3.5GHz but frequencies in the 26GHz to 300GHz range will be utilised. You can see where the maths is going to take us. At 26GHz, the same equations above would suggest a speed of 78Gbps would be possible. Initially, at least, that won’t happen in the real world but theoretical speeds of 30Gbps will be possible.

Now for the down side. Wavelength is indirectly proportional to frequency. 700MHz delivers a wave that is 42.9cm long. At 26GHz the wavelength is 1.2cm long. Why do we care? In practical usage terms, we want radio waves to pass through walls and trees and people. Longer wavelengths are better able to pass through materials but shorter wavelengths are more easily absorbed. At high enough frequencies, even the atmosphere starts to absorb more signal. Initially water vapour and then other atmospheric gases attenuate the signal.

On the good side for users in regional Australia, whilst 5G may not help the reception when users are at a certain distance from a tower, the introduction of 5G at higher frequencies is likely to reduce the congestion on lower frequencies for 4G usage which may well help the reception for 4G users.

If you can’t get enough tech from this weekly article alone, search for ‘Tech Talk by Mathew Dickerson’ on your favourite podcasting app for my weekly podcast.

Mathew Dickerson

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