The first in a series of 5G explainer articles, read this to find out about the three 5G spectrum layers; the differences, the use cases and why they’re important.
The Basics: Radio Signals
Your phone and other devices connect to the mobile network using radio signals. These electromagnetic waves transfer data back and forth between device and mast, allowing you to access the Internet, make calls, and send messages.
Mobile networks have always operated using radio signals going back to previous generations. While the basic principle remains the same, one of the key developments of 5G is that is expands the range of frequencies available, to dramatically improve performance.
Network Performance and Frequency
The frequency used to connect to the mobile network plays a significant role in defining the properties of your connection. This includes:
• Bandwidth – the rate of data transfer, measured in Megabits (Mbps) or Gigabits (Gbps) per second.
• Latency – the time delay between a user’s action and the response, measured in milliseconds (ms).
• Coverage – How close to a mast you must be to receive a signal.
5G introduces higher frequencies which offer significant bandwidth and latency improvements – but the higher the frequency, the more limited the signal range and coverage becomes. 5G’s three spectrum layers, Low-Band, Mid-Band and High-Band, have different trade-offs between coverage and performance which allows 5G to cater to different applications and locations:
The Three Spectrum Layers of 5G
The Low-Band spectrum is the lower performance “Coverage Layer”, ideal for reaching every user nationwide. The exact frequency range the Low-Band spectrum operates at differs from country to country. For example, in the UK, Low-Band 5G operates at 700MHz.
This base level 5G performance is able to reach hundreds of square miles from a single mast, ideal for low population density, rural locations. Another factor to consider is that these longer-range radio signals can easily pass through obstacles such as walls.
While Low-Band 5G doesn’t offer the game-changing performance that enables exciting new applications such as smart cities and autonomous vehicles, it still offers speed improvements compared to 4G.
Mid-Band 5G operates at significantly higher frequencies (3.4GHz) than the Low-Band layer and existing 4G networks (in the UK, for example, the maximum 4G frequency is 2.6GHz). It is also known as the “Capacity Layer” or “C-Band”, and is believed by many to be the ideal layer.
As you might expect, the Mid-Band spectrum offers a middle ground between performance and coverage – higher speeds than the Low-Band and better coverage than the High-Band. A single mast with Mid-Band radios can provide connections to a radius of several miles, ideal for metropolitan areas.
Part of the reason the Mid-Band layer can offer higher bandwidth is due to the more extensive range of frequency available compared to the Low-Band spectrum.
Operating above 6GHz, High-Band spectrum offers the true potential of superfast, high performance 5G networks. These high frequency bands are also known as “mmWave” and the “High-Capacity Layer”.
This performance comes at the price of having very low range and obstacle penetration. The absolute maximum range of High-Band 5G antennas is one mile. But with signals being so easily absorbed, even this distance isn’t easily achievable. Certain types of glass and walls can completely absorb High-Band 5G signals. For this reason, this layer will take some time to fully build out in public networks.
In the UK today, for example, operators have secured spectrum for Mid-Band 5G but true High-Band frequencies haven’t yet been auctioned by Ofcom – though it is known to be freeing up space in the 8GHz and 26GHz bands, expected to be available by the end of 2022.
High-Band 5G is suited to dense urban areas and areas where people gather, such as stadiums and shopping centres.
Why All Three Spectrum Layers Are Vital to 5G
While there is a lot of buzz about 5G and its performance in different scenarios, the reality of 5G will be a mix of all three spectrum layers to ensure users get the right blend of coverage and performance for their given situation: