Data Services on Shared Private Mobile Radio (PMR) Channels

Policy statement by the Radiocommunications Agency

Introduction

A PMR service is used to pass messages to, from or between, mobile units as an aid to conducting a business or for providing a professional or public service. In simplest form a PMR service provides communication solely in the form of speech and the majority of channels, which are shared, have been used for speech only, except for non-speech tone signalling. A new class of PMR channel for a small number of data-dominant channels is now being introduced and the use of data on speech-dominant channels is being extended.

2. The Agency has recognised that there is a special requirement for intensive use of data traffic on PMR channels by some business users and has therefore decided to introduce data-dominant channels in VHF Low and Mid Bands. To provide value added services for existing PMR users on shared speech-dominant channels, the Agency has decided to licence additional data facilities. These will cover all forms of data transmission, including those currently authorised under Condition 28 of the existing Licence Guidance Notes which concerns signalling methods.

3. There are two options described below. The interim access protocol is intended for use with existing unmodified PMR equipment on speech-dominant PMR channels. The more sophisticated protocol, MPT 1379, will apply to both speech-dominant and data-dominant PMR channels.

Interim Access Protocol

4. PMR systems using the interim access protocol at Annex A will be approved subject to new licence conditions. Equipment type approved to the following performance specifications may use the interim access protocol: MPT 1301, 1302, 1303, 1304, 1326, ETS 300 086 and I-ETS 300 219. However W specification equipment will not be permitted to use it.

5. Users who wish to use the interim access protocol will need to submit application form RA1 to the Agency or the Agency's District Office with additional details about the identification code and data format included. Licensed users will be able to use this protocol until 31 July 2000. Typically the relevant licence clause will say:

"Manual initiated data transmission and automatic acknowledgement, by either direct modulation or any form of audio signalling, digital or multiple tone sequence is permitted provided that:

1. the message length does not exceed 500msecs and total channel occupancy 650msecs or where in-band tone signalling and/or CTCSS is used in conjunction with a digital data message the total channel occupancy shall not exceed 1 second;
2. no data messages as defined above shall be transmitted more than once in every five transmission periods; and
3. no automatic retries are permitted; and
4. the identification code and message format is [as appropriate];

Condition 28 of PMR Licence Application Guidance Note

6. The interim access protocol has replaced Condition 28 of the PMR Licence Application Guidance Notes which covers the limited tone signalling currently permitted on shared PMR channels. The provisions of Condition 28 dealing with data transmission were withdrawn on 30 September 1993, although existing equipment installed under this condition may continue to be used by existing users until 31 July 2000.

MPT1379 Access Protocol

7. The MPT 1379 access protocol is a development of I-ETS 300 113 and requires that radio equipment be fitted with a 'carrier sense' facility. It has been notified to the European Commission under Directive 83/189 as a technical regulation. Once cleared, it will be published and data services on shared channels using this protocol will then be licensed on a case by case basis.

Timescales

8. The Agency will phase in the new rules in the following way:

Interim Access Protocol

17 August 1993
Start licensing of existing and new equipment using interim access protocol.

30 September 1993
Condition 28 of the PMR licence application guidance notes as it applies to data trans-mission and selective calling withdrawn.

31 July 1995
Cease giving new licensees authorisation to use interim access protocol

31 July 1998
Cease giving authorisation to existing licensees (ie licensed prior to 31 July 1995) to use interim access protocol.

31 July 2000
All equipment using the interim access protocol to be phased out by this date.
All new and existing data equipment (ie on both speech and data-dominant channels ) to use MPT 1379 access protocol.

MPT1379 Access Protocol

July 1993
Notify MPT1 379 access protocol to European Commission under Directive 83/189.

October 1993
Publication date for MPT 1379.

31 July 1995
All data equipment for new licensees must be compliant with the requirements of MPT 1379.

31 July 1998
All new licences and authorisations for existing users for data transmission must be in respect of equipment meeting the MPT 1379 access protocol.

Condition 28 of PMR licence Application Guidance Notes

30 September 1993
No further installations of data transmission equipment permitted under condition 28.

31 July 2000
All data equipment permitted under Condition 28 to be phased out by this date. All new and existing data equipment to use MPT 1379 access protocol.

Data Dominant Channels

1August 1993
Begin ad hoc licensing of equipment

October 1993
Publication of MPT 1379. End ad hoc licensing arrangements. Any existing licensees to comply with published MPT 1379 access protocol within one year. All new users assigned data-dominant channels required to comply with MPT 1379 access protocol immediately.

9. The Agency will review this timescale in the light of market developments within the next two years.

10. For information on other radio matters contact the Agency's 24 hour Telephone Enquiry Service Tel: 020 7211 0211

Interim Access Protocol – Annex A

1. Manual initiation only is permitted (automatic acknowledgement is permitted) with no automatic retrial procedures.

2. The total channel occupancy for transmission of a message shall not exceed the following length for the respective signalling type:

1. digital data transmission - 650msec;
2. digital data transmission used with CTCSS and/or in-band tone signalling - 1 second (see note):
3. in-band audio tone signalling - 650msec; and
4. in-band audio tone signalling with CTCSS - 1 second.

3. Message repetition from any transmitter shall not exceed one in five. This means that a data message may only be initiated in one time slot out of every five slots dependent on signalling type as defined above.

4. All systems operating to the interim access protocol may continue to be used on a non-interference/no-protection basis until 31 July 2000.

5. The Licensing of new services using the interim access protocol will be possible up to 31 July 1995 after which all applicants will be required to use MPT 1379.

6. Any form of audio tone signalling carrying data messages already operating on shared voice channels may continue on a non-interference/no-protection basis until 31 July 2000.

Note
This can encompass the CTCSS encoder/decoder response times (50/250msecs respectively - values taken from MPT1306) combined with a 500msec data burst and power up/down times. The time interval also allows a 5 tone sequence plus approximately 500mSec worth of data (420msec worst case and 510msec best case - values taken from MPT 1316) to be conveyed.

Radiocommunications Agency
Wyndham House
189 Marsh Wall
London
E14 9SX

Tel: 020 7211 0211

website: www.radio.gov.uk

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