What Is 5G and How Does It Work?

As a society that is becoming increasingly dependent on data driven applications, 5G promises to provide better connectivity and faster speeds for our network devices. However, whilst the previous generations of mobile communications have been fairly analogous to each other in terms of distribution and multiple user access, 5G will be drastically different – making it a challenging system to implement. So, how does it work?

Initial Concept

Fig 1 – The 5G Triangle

As with any concept, 5G was initially based on a very broad set of standards which promised low latency, speeds in the region of Gbps and better connectivity. Whilst no intricacies of the system were known at the time, we knew that in order to achieve faster data rates and larger bandwidths we would have to move to higher frequencies – and this is where the problem occurs. Due to the physical limitations that high frequency signals are subject to, such as atmospheric attenuation, range and power become serious issues that our current systems simply can’t overcome.

Range & Power

A modern GSM tower features multiple cellular base stations, that together, are designed to transmit over 360⁰ (horizontally) and at a range of tens of miles – depending on the terrain.  However, if you were to consider that the power transmitted from a cellular base station degrades with distance at a rate of…

(1)

And that by factoring in frequency, this effect worsens…

(2)

…it becomes obvious that transmitting over larger distances becomes exponentially inefficient. Therefore, a key part of the 5G overhaul would involve the installation of thousands of miniature base stations, aka femtocells. These would need to be strategically placed in our dense, urban environments in order to maximise capacity with minimal obstructions.

Directivity

One way to increase the range of  an antenna structure, whilst keeping the power output the same, is to introduce gain via the antenna. This is achieved by focusing  the transmitted power towards a particular point as opposed to equally in all directions (isotropic).

Fig 2 – Radiation Pattern of an Isotropic Antenna versus an Antenna with Gain  (Dipole)

Figure 1 shows such a comparison, in which, a dipole antenna’s energy is being focused in the direction of 180 and 0 degrees. Equation three reflects this additional factor:

(3)

However, as the essence of a wireless handset is portability, it is likely to move around a lot with the user. Therefore, a high gain 5G transmitter would still require a tracking system to ensure that it stays focused directly at the end-user’s handset.

User Tracking

One solution for tracking devices could be to employ a high frequency transceiver with a phased array antenna structure. This would act as a typical base station, capable of transmitting and receiving, but an array of hundreds of small scale patch antennas (and some DSP magic) would make it capable of beam forming. This would not only allow the structure to transmit high gain signals but to also steer the beam by changing the relative phase of the output.

However, as this is a technically complex system that has yet to be implemented on such a large scale, this is still only realisable in research and design labs under a controlled set of criteria. Considerable efforts will have to be made to ensure that such a transceiver could operate in a bustling environment where multipath and body-blocking would  cause strong interference.

5G in 2019

3GPP (the 3^rd Generation Partnership Project) is an organisation that was established in 1998 and helped to produce the original standards for 3G. It has since gone on to produce the specs for 4G, LTE and is currently working to achieve a 5G “ready system” in 2020.

With certain service carriers already having released 5G this year in certain parts of America, 2019 will be welcoming numerous 5G handsets from several of the flagships giants like Samsung, LG, Huawei  and even Xiaomi – a budget smartphone manufacturer.

As with previous systems though, only limited coverage will be available at first (at a premium), and in practice, it will be fairly similar to Wi-Fi hot-spotting. A lot of work is still required to overcome the issues as discussed above.

References / Notes

1. Fig [1] – https://futurenetworks.ieee.org/standards
2. Equations [1], [2] and [3] are approximations only of Frii’s power transmission formula and do not represent the full derivation.
3. Fig [2] – https://bit.ly/2UpGn8F