A quick guide to 5GHz in the UK - Part 1
Operating in the 5GHz spectrum can be a bit of a minefield if you don't know what you are doing. In comparison, 2.4GHz is relatively simple – Just pick a channel between 1 and 11 (in some cases you can include 12 and 13 - although this is not best practice) and keep to no more than 100mW effective radiated power and all is groovy. With 5GHz however your legal limits are defined by which frequency you are operating within and which frequency you need to operate within is defined by your link requirements.
The 5GHz spectrum in the UK runs from 5150MHz (5.15GHz) to 5850MHz (5.85GHz). This is then broken down into 3 different bands (Band A, B and C). Each band has its own maximum allowed effective radiated power output and specific rules as to where it can be used and whether a license is required to operate within it.
Band A (Channels 36 – 64)
This is used for Indoor wireless only and does not require a license. It is a 200MHz wide band which allows for 8 x 20MHz channels to coincide without overlap or 4 x 40MHz. The maximum output power is 200mW which is double the allowed output power of 2.4GHz. Now you may be thinking "great – my wireless is going to transmit further!"… Unfortunately, its not quite that simple as the wavelength of 5GHz is roughly half that of 2.4GHz meaning you need to transmit at twice the power to get the same distance. Due to the shorter wavelength, 5GHz also has the worse penetration than 2.4GHz so doesn't pass through walls and obstacles as well, it does however scatter much better.
I will cover this in more detail in part 2 of the blog, but the bottom line is for indoor use 2.4GHz should be your weapon of choice unless the 2.4GHz spectrum is too crowded or your building is open plan.
Band B (Channels 100 – 140)
Band B is also license free and can be used both inside and outside. It has a higher permitted output power of 1000mW (1W). Being 255MHz wide it allows for 10 x 20MHz channels to coincide without overlap or 5 x 40MHz channels. All hardware operating in Band B must conform to DFS (Dynamic Frequency Selection) standards and DFS must be enabled
Band C (Channels 149 – 161)
If the 1000mW output power limit that Band B offers isn’t enough to suit your needs, then have no fear – Band C is here! Band C can be used with output powers of up to 4000mW (4W). There are some conditions however:
a) Band C can only be used for outdoor wireless
b) Band C can only be used for fixed wireless access (FWA) points (e.g point to point or point to multipoint links)
c) A light license is required for operation and must be purchased from Ofcom.
d) All hardware must conform to DFS (Dynamic Frequency Selection) standards and DFS must be enabled
Band C is 125MHz wide and allows for 4 x 20MHz channels to coincide without overlap or 2 x 40MHz channels.
Licenses For 5GHz in Band C
If you plan to use 5GHz in Band C then you will need to get yourself a shiny bit of paper from Ofcom stating that you have permission to do so! Now before you start getting worried about being hit for hefty licensing fees, let me set your mind at ease… Currently a Band C license costs a mere £50 a year for up to 50 devices and for each additional device you want to register, it is an extra £1 per year. Now that’s ASDA price!
Applying for a Band C License
So you've decided to be good and abide by the laws set by Ofcom… Your first job is to apply for a Band C License. You can apply for one by filling in the following form
and sending it to:
Ofcom Contact Centre
Ofcom
Riverside House
Southwark Bridge
London
SE1 9HA
Once authorized you will be provided with a license certificate by Ofcom. Your next step now is to register your hardware by visiting:
https://secure.ofcom.org.uk/opir/
Once registered, you can start using Band C, but only for the devices you have registered.
If you have any other questions about the Ofcom registration process and requirements, then you may find the answers by visiting the FAQ and/or requirements guide at:
http://licensing.ofcom.org.uk/radiocommunication-licences/fixed-wireless-access/faqs
If you enjoyed this article and would like to continue onto Part 2 of this guide, it can be found here: https://www.digitalairwireless.com/articles/blog/quick-guide-5ghz-uk-part-2