Get permission to use the airwaves

Understand what you are applying for

A frequency identifies a position in the radio spectrum. MHz means megahertz. A channel occupies a range of frequencies around a centre frequency. Bandwidth describes the width of that channel. Your base station, its settings and the permission issued for your site must agree.

Band 40 is an equipment capability. It covers 2300 to 2400 MHz using time division duplex, usually shortened to TDD. TDD means the base station and phone take turns transmitting in the same channel. Owning a Band 40 radio does not give you permission to use the whole band. See the operating band and channel numbering tables in 3GPP TS 36.101, published by ATIS.

Ofcom offers a Shared Access licence for local networks. Its current 2.3 GHz spectrum blocks are 2320 to 2340 MHz and 2390 to 2400 MHz. These are separate blocks, with other uses between them. The licence you receive will identify what you may actually use. Start with Ofcom's Shared Access licensing page whenever you plan a new installation.

Choose the indoor low power route

For this beginner build, plan to keep the base station and its transmitting antenna indoors. Ofcom's April 2026 guidance says ordinary Shared Access licences in the 2.3 GHz band are available for indoor low power use. Outdoor low power and medium power operation in this band are not standard options. A radio sold as outdoor equipment does not change that rule. Do not describe an antenna mounted outside as an indoor installation because its power supply or computer is inside.

A low power licence authorises base stations within a circle of 50 metres radius around the licensed coordinate. Draw that circle on your site plan and mark each proposed base station. The circle concerns base station placement. It does not promise that every phone within 50 metres will receive a useful signal, or mean that signal stops at the circle's edge.

The 2320 to 2340 MHz block is unavailable within the Salisbury Plain Training Area. Check the current Shared Access guidance, sections 2 and 3. If your intended installation is outdoors, resolve the licensing route with Ofcom before buying a radio for that purpose.

Check the exact radio before you buy it

Ask the supplier for the exact Baicells model number, hardware variant, supported frequency range and firmware version. A listing that says only LTE or Band 40 is not enough to choose a suitable unit. Ask the supplier to confirm, in writing, that this specific radio can use the proposed channel and bandwidth and can reduce its radiated power to the limit on your licence.

Also request the installation manual, antenna specification and declaration of conformity for that model. Record whether the antenna is built into the unit or connected separately. Find out whether the radio's power setting means power per transmit chain, total transmitter output or radiated power. These are different quantities. Keep the supplier's answers with your network records so the next person can understand the installation.

Radio equipment supplied in Great Britain must meet the applicable product requirements. The government's Radio Equipment Regulations guidance explains conformity marking, documentation and supplier responsibilities. Product conformity and a spectrum licence answer different questions: the first concerns the equipment; the second authorises its use under specified conditions.

Prepare an application folder

Create a folder called Spectrum application. Put your site plan, equipment documents and the following information in it before you open the licensing portal. This is a preparation checklist, so some details are for your own installation record rather than separate mandatory portal fields.

1. Record the legal name and address of the person or organisation that will hold the licence, a working email address, a telephone number and billing details.
2. Write the installation's full postal address and a short name that you will recognise later.
3. Find the centre coordinate for the proposed low power area. Record a precise UK National Grid Reference or coordinates in a format accepted by the portal. Check that the point is on the intended building, not a postcode centre or nearby road.
4. Mark the 50 metre radius, building boundaries and proposed indoor base station positions on a plan.
5. Record the proposed spectrum block and 10 MHz bandwidth. Keep the requested values separate from the values eventually granted.
6. Save the radio model, firmware, antenna model, antenna gain, cable details and the completed power worksheet below.
7. Write a short description, such as private indoor LTE for authorised test phones and local data access, together with the intended start date.

Ofcom's application form illustrates the identity, location and technical information involved. Its older frequency examples do not replace the current portal or guidance.

Apply, pay and read the issued licence

Follow the licensing portal link on Ofcom's Shared Access page, create or sign in to your account and select the Shared Access product. Choose the indoor low power option appropriate to this build. Enter the prepared details carefully and save the application reference.

Ofcom assesses the application before offering authorisation. An application receipt is not a licence. An invoice is not a licence. Pay an approved application's invoice as instructed, then wait for the actual licence document. Read its assigned channel, bandwidth, site details, power limits, commencement date and conditions before enabling RF. Keep a local copy that you can still read if your internet connection is unavailable.

The current published charge for a low power 10 MHz channel is £80 per year for each licensed area. Budget for the recurring fee as well as the hardware. Check the amount on Ofcom's page when applying. More areas or channels can change the total cost. If a detail on the issued licence differs from your plan, resolve the difference before using the radio.

Enter frequency and bandwidth without guessing

For an illustration only, suppose your issued licence authorises a 10 MHz channel spanning 2390 to 2400 MHz. Its centre is 2395 MHz. An LTE interface that asks for the Band 40 EARFCN would use 39600 for that centre. EARFCN is simply LTE's channel number. This follows the frequency formula and Band 40 offset in section 5.7.3 of 3GPP TS 36.101. Copy your own granted values, not this example by habit.

A 20 MHz channel cannot fit inside the 2390 to 2400 MHz block. The separate 2320 to 2340 MHz block is physically 20 MHz wide, but that does not mean a single 20 MHz Shared Access carrier is automatically authorised. Ofcom's April 2026 guidance describes the current offering as 10 MHz channels and notes that a 20 MHz option for the wider block was not yet available at publication. Check the current offering and your grant before changing bandwidth. Two permissions for smaller channels should not be treated as permission for a wider carrier without explicit authorisation.

Understand dBm, dBi and the power limit

The radio's output setting is only one part of the power calculation. dBm expresses an absolute power level relative to one milliwatt. dBi expresses antenna gain relative to an ideal reference antenna. dB expresses a ratio such as cable loss. You can add gain and subtract loss when all the quantities use these logarithmic units.

EIRP describes the effective radiated power in the strongest direction. The January 2025 IR 2103 interface requirement, table 3.2 specifies 24 dBm EIRP per carrier up to 10 MHz for low power base stations in this spectrum. That is approximately 251 mW EIRP. It is not permission to set every transmitter port to 24 dBm or to use a radio at its advertised maximum output.

Ofcom explains how transmitter output and antenna gain affect radiated power in its guidance on calculating EIRP and ERP. Use manufacturer information for the complete radio and antenna arrangement. Keep EIRP and ERP distinct, and do not substitute an antenna figure labelled dBd for one labelled dBi.

Complete a simple power worksheet

For a simple single transmit chain, write down the transmitter output, subtract cable and connector losses, then add antenna gain. The result is the EIRP estimate. These invented numbers show the arithmetic; they are not Baicells installation settings.

In this single chain example, 22 dBm is about 158 mW. A 30 dBm output would instead produce 35 dBm EIRP with the same antenna and cable, which is about 3.16 W. A small difference in the dBm figure can represent a large difference in watts.

LTE radios commonly have multiple transmit chains. Their powers cannot be combined by adding their dBm numbers. Two equal independent contributions can add roughly 3 dB to total power, but the relevant radiated maximum depends on the antenna arrangement and transmit behaviour. Ask the supplier to confirm the complete equipment's compliance with the per carrier limit, including every chain. For an integrated antenna, obtain the manufacturer's radiated power figure instead of inventing an internal cable loss. Leave headroom for tolerances and save the approved setting.

Keep RF disabled during preparation

You can prepare the Ubuntu computer, core software, addresses and configuration files while the base station's RF function remains disabled. Find the manufacturer's RF disable control before connecting power to an unfamiliar radio, because some equipment can resume transmitting after a restart.

There is no general exemption that lets you transmit cellular signals because the equipment is a software defined radio, the network is private or the purpose is learning. A SIM card and a low power setting do not replace authorisation. Do not assume that attaching a dummy load or putting equipment in a box makes an unlicensed radiating test permissible.

If your work needs a separate experimental radio test, read Ofcom's innovation and trial licensing information and resolve the appropriate authorisation first. That product is for temporary, noncommercial experimentation and does not replace permission for an operational network. For this build, the clear checkpoint is possession of the applicable licence before enabling RF.

Save evidence and review changes

Keep the issued licence, payment reference, site plan, radio and antenna specifications, power calculation and final configuration export together. Add a photograph of the installed unit and antenna, with a note identifying the room and mounting position. Make a short change log whenever you move equipment or change power, bandwidth, frequency, antennas or firmware.

Before enabling the radio, compare your configuration against the licence line by line. Ask a second person to read back the site, indoor status, channel and power if one is available. After a power cut or firmware update, confirm that the saved settings have returned correctly. If you later move to another building, do not assume the original location's permission travels with the hardware.

Licence conditions can include deployment records and frequency changes required by Ofcom. The example conditions in Ofcom's Shared Access framework statement explain why those records matter. Use your issued document as the final checklist. Complete this chapter when your authorisation, site plan and configured radio all describe the same installation.