1. Introduction

This information sheet outlines the technical frequency assignment criteria and assignment principles used by the Radiocommunications Agency (RA) in selecting frequencies for use by Private Business Radio (PBR) systems. Details of the licence products and frequency bands available for these services are published in RA's 'United Kingdom Plan for Frequency Authorisation' (see Section 5).

This sheet is not a comprehensive description of the complex engineering procedures that RA employs when assigning frequencies for PBR, but it provides an overview of the general principles and criteria used. Details of our assignment procedures for PBR are available in the PBR Licensing Procedures Manual (see Section 5).

If you have detailed questions about the criteria, please contact our Private Business Systems Unit (see Section 5).

2. Technical frequency assignment criteria

Technical frequency assignment criteria describe the technical principles and guidelines used by RA to identify which particular radio frequency or radio frequency channel(s), from the bands specified for the relevant licence type, are available for authorisation at any particular location and under what technical conditions.

Technical frequency assignment criteria may limit (or prevent) the availability of a licence, and/or grants of rights under a licence, at a particular location if this is necessary to prevent interference to existing services.

3. Assignment criteria for PBR systems

When making an assignment, we apply formalised assignment criteria in concert with the expertise and judgement of our assignment staff, with the aim of achieving the most efficient use of the available spectrum and avoiding interference. Our criteria and processes will ensure that:

the distance to the nearest base stations operating on the same frequency (co-channel) does not fall below the minimum required separation -this minimum distance will vary for different types of service and according to the transmitter's location;

the mobile loading on the channel does not exceed a level that would prevent access to the channel by new or existing users;

the geographical location of the proposed assignment is carefully considered when deciding its viability;

the type of service required by the applicant is appropriate for the available channels in the desired geographical location; and

the technical restrictions required (e.g. maximum antenna height above ground level and maximum base station ERP) are defined so as to ensure the best possible use of the available spectrum.

RA makes all assignments on the basis that PBR channels are for shared use. Our assignment procedures allocate assignments, not on a 'best channel first' basis, but on the basis that the channel meets our minimum requirements. These measures ensure that access to PBR spectrum in any particular location remains available for as long as possible.

It is becoming increasingly difficult to make new PBR frequency assignments in the major conurbations, particularly in VHF High Band and the UHF bands where demand is high. While we do our best to satisfy requests for assignments in these bands, we also try to make prospective licensees aware that other, less congested, bands are available. These bands may have the advantage of a better quality assignment (less sharing) - and, under spectrum pricing arrangements, they may attract a lower licence fee.

Geographical limitations (geolimits)

There are geographical areas of the UK where a single channel, groups of channels or a complete band are not available for making PBR assignments.

There are a number of reasons for this. The two most common are that the spectrum is already in use by other non-PBR services in the area, or that the area contains particular types of PBR service which require greater protection from interference than normal services (e.g. safety-critical services).

International co-ordination

During the assignment process, we may need to conduct co-ordination with the administrations of neighbouring countries. A range of international agreements and treaties defines the field strengths of radio transmissions allowed at borders before international agreement must be sought. If a particular assignment exceeds the relevant field strength limit, international co-ordination will be initiated. The co-ordination process is designed to minimise the potential for interference across borders.

Co-ordination with other organisations

Because of the PBR frequency bands' close proximity to bands used by the emergency services etc, we may need to co-ordinate assignments with these other users in order to avoid potential interference.

4. Site clearance

Site clearance is a procedure that protects sensitive sites on safety and security grounds. The procedure is triggered when:

radio equipment is intended to be used with power levels of at least 17 dBW (50 watts) effective radiated power (ERP);

the antenna height is more than 30 m above ground level; and/or

the antenna adds more than 5 m to the existing height of the supporting structure.

In these cases, the licensee must apply to us, and we will ask the Government's site clearance committee (which includes the relevant UK Government safety and security agencies) to decide whether the site is acceptable.

In practice, since only a very small number of PBR transmitter stations have an ERP of 50 watts or more, and most high sites have already been site-cleared, only a handful of cases will have to undergo site clearance.

5. Further information

The 'United Kingdom Plan for Frequency Authorisation', the PBR Licensing Procedures Manual and many other RA publications are available free of charge on our website (www.radio.gov.uk) and from:

Information and Library Service
Radiocommunications Agency
Wyndham House
189 Marsh Wall
London E14 9SX

Tel: 020 7211 0502/0505
Fax: 020 7211 0507

For further information on this or any other matter regarding private mobile radio, please email our Private Business Systems Unit at pbs.enquiries@ra.gsi.gov.uk, or write to:

David Thomas
Private Business Systems Unit
Radiocommunications Agency
Wyndham House
189 Marsh Wall
London
E14 9SX
Tel: 020 7211 0182

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