Audit of Land Mobile Radio Use in Sub Bands1 and 2 of Band III in the London Area

Overview of findings obtained from licensing and monitoring information relating to occupancy of channels.

Report prepared by Private Business Systems Unit and Baldock Mobile Monitoring Group of the Radiocommunications Agency

CONTENTS
Introduction	Paragraph
Background	0.1 - 0.5
Objectives & Methodology	0.6 - 0.12
Summary
Number of Services	1.1 - 1.2
Channel Occupancy	1.3 - 1.4
Composition of Sub Bands 1 and 2 of Band III
Description	2.1
Channel Allocation	2.2
PAMR / Private Users Channels	2.3
Public Mobile Data Network Channels	2.4
Public Access Mobile Radio Channels	2.5 – 2.6
National Channels	2.7
Unallocated Channels	2.8
Monitoring Survey
Method	3.1
Unattended Monitoring Systems	3.2 - 3.5
Location of Monitoring Sites	3.6 - 3.8
Monitoring Results	3.9 - 3.11
Monitoring & Licensing Data
Channel Analysis	4.1 - 4.2

0.1 In July 1992 a review was commissioned aimed at examining current use of the radio frequency spectrum from 28-470 MHz and making recommendations in the light of developments.

0.2 The Report of the Review Committee was published in March 1994 (Report of the Radio Spectrum Review Committee Stage 3: 28-470 MHz; ISBN 1 85569 172 8). A response to the Report was published in April 1995 (ISBN 1 85569 172 8). Copies of the Report and the Response are available from:

0.3 One of the recommendations of the Review Committee was that "The existing mobile radio allocations in London should be the subject of a detailed "spectrum audit" to establish whether they are adequate to cope with current demands".

0.4 The Radiocommunications Agency is responding to this recommendation by carrying out audits of the land mobile radio bands on a band by band basis. Reports have been completed on VHF High Band, VHF Mid Band, UHF 2, UHF 1, and VHF Low Band :

"Survey of Land Mobile Radio use in VHF High Band in London" (ISBN 185569 1981) published in March 1995;

"Audit of Land Mobile Radio use in VHF Mid Band in the London area" (ISBN 185569 2333) published in September 1996;

"Audit of Land Mobile Radio use in UHF 2 Band in the London area" (ISBN 185569 2694) published in March 1998;

"Audit of Land Mobile Radio use in the UHF 1 Band in the London area" published in December 1998;

"Audit of Land Mobile Radio use in VHF Low Band in the London area" published in April 1999.

0.5 This Report is the last in the series and covers the audit of sub bands 1 & 2 of Band III. It provides details of land mobile radio services operating on frequencies in the two sub bands (177.20625 - 191.49375 MHz and 193.20625 - 207.49375 MHz) and channel utilisation data gathered by the Agency’s Mobile Monitoring Group.

(a) establish the accuracy of the Agency’s licensing data, in particular data relating to the technical characteristics of Band III radio services, numbers of mobiles in use, and location of services;

(b) monitor radio traffic on Band III channels so as to establish current loadings;

(c) analyse the data obtained from (a) and (b) above in order to draw conclusions on the current loading of Band III channels in the London area.

0.7 The Agency contacted all Band III licensees operating radio services from sites located within a radius of 30 kilometres from Central London (NGR: TQ 300 800). They were asked to confirm that the details recorded on their licence schedule(s) were correct.

0.8 Licensees who did not reply were contacted by staff from the Agency’s Local Office. The Local Office staff assisted these licensees in the verification of the schedule details.

0.9 Unlike the other major land mobile radio bands, Band III is used mainly by large public and private radio systems such as Public Access Mobile Radio (PAMR) networks (national and regional), a national public mobile data network, local government trunked radio systems, railway operators, and bus & coach companies. There are few of the single channel services which predominate in the other bands. There is, therefore, only a limited number of licensees operating in the London area on Band III channels. Of the 14 licensees affected by this audit the licensing data of 4 has been verified by the Agency’s Local Office.

0.10 The Agency’s Mobile Monitoring Group at Baldock obtained radio traffic data, including details of the busy period for each base transmit frequency and each mobile transmit frequency. Information was gathered through the installation of 7 unattended monitoring systems (UMS), located around Greater London. Details of the methodology employed are set out in Section 3 of this Report.

0.11 An analysis of overall channel loadings, based on the full range of channels surveyed, is at Section 4 of this Report; together with a sample of individual channel analyses. A full individual analysis for each of the 494 channels in sub band 1 and 503 channels in sub band 2 is contained in Parts II and III of this Report; together with information on the services which operate on these channels.

0.12 The Agency would welcome any views or comments on the contents of this Report. Please send your comments to:

Ray Wilson
Radiocommunications Agency
Private Business Systems Unit
Wyndham House
189 Marsh Wall
LONDON E14 9SX

a) 163 radio services operating on the 494 dual frequency channels in sub band 1 of Band III in the London area (an average of 0.33 services per channel);

b) 315 radio services operating on the 503 dual frequency channels in sub band 2 of Band III in the London area (an average of 0.63 services per channel).

Note: a radio service in this context means a base station with an associated radio channel. A base station with eg three associated radio channels, has been counted as three services.

1.2 The average number of services per channel for the various channel categories in sub bands 1 and 2 is as follows:

Sub Band 1
PAMR / Private users channels	0.35
Public Mobile Data Network channels	0.59
Sub Band 2
PAMR channels	0.45
National channels	1.42

1.3 Monitoring of the 494 sub band 1 channels indicated that 34.6% achieved a peak occupancy level of between 0.5 and 1 Erlang. 53.3% of the 503 sub band 2 channels achieved this level of occupancy.

1.4 The rates of occupancy varied according to the types of radio service operating on the channels. For each of the channel categories covered by the audit the percentage of channels in the 0.5 to 1 Erlang range was as follows:

Sub Band 1
PAMR / Private users channels	35.9%
Public Mobile Data Network channels	69.4%
Sub Band 2
PAMR channels	52.1%
National channels	62.1%

2.1 Private Business Radio and Public Access Mobile Radio use of sub bands 1 & 2 of Band III is contained within the ranges 177.20625 - 191.49375 MHz and 193.20625 - 207.49375 MHz (band edges) providing a total of 997 channels.

2.2 There are 494 dual frequency channels in sub band 1 and 503 in sub band 2. They use 12.5 kHz channel spacing and are designated for use by Private Business Radio and Public Access Mobile Radio services, and a national public mobile data network, as shown in Tables 1 and 2 below:

2.3 PAMR / Private Users channels are available to either Public Access Mobile Radio operators (see paras 2.5 and 2.6 below) or private users on an area, or regional, exclusive basis. Private uses include radio services operated by local government and public transport organisations.

2.4 The Public Mobile Data Network which operates in sub band 1 provides a national, data only, communications service which is offered to subscribers on a commercial basis. Typical uses of mobile data networks include despatch operations and vehicle location/status messages.

2.5 Public Access Mobile Radio (PAMR) systems provide wide area trunked mobile radio communications services, on a commercial basis, to a number of independent users. PAMR operators in Band III offer analogue (mainly voice) communications between mobiles and their dispatchers, without call set-up as in cellular-type systems.

2.6 Following mergers in recent years, there is now effectively only one national PAMR system. This system operates on sub band 2 channels. In addition there are several independent regional systems operating on channels in both sub bands. Typical customers of the PAMR operators include service engineers and road hauliers

2.7 Band III users in this category comprise two licensee groups; the bus and coach industry (64 channel allocation) and the railways industry (31 channel allocation). Users operate on channels which are allocated for the sole use of members of their group throughout the United Kingdom.

2.8 The unallocated channels are a resource which has yet to be earmarked for any particular purpose but which could be used for future growth of existing services, for new services, or for future exceptional circumstances.

3.1 Monitoring was performed at 7 sites selected to represent the majority of London, within the M25. The monitoring was undertaken by unattended monitoring systems (UMSs) located at secure sites. Computed predictions have been made to indicate the area in which contributions from mobiles would be accounted for within the monitoring results. The general principle is shown in Figure 1 on Page 8.

3.2 The monitoring techniques used allow the unattended monitoring systems to capture data over 24 hours, 7 days per week.

3.3 The UMS contains a programmable receiver which is fitted with a tracking pre-selector and switchable RF attenuators, the latter enables system performance to be verified. The system is controlled by a dedicated computer that can be programmed locally or by remote modem link. The complete system can be configured, programmed and data extracted by the Agency’s Mobile Monitoring facility based at Baldock in Hertfordshire.

3.4 The UMSs measure field strength, by applying cable loss and antenna factor to the voltage measured by the receiver. This level is then compared to the threshold set in the configuration file. Values above the threshold increment the occupancy register. The field strength is also recorded and a report detailing max, min and average field strength, together with occupancy is created for each channel monitored. Results are reported for every 15 min period. Both peak and average detectors can be selected, however the average detector is used for this type of monitoring exercise. The scan rate is approximately 2000 channels per second.

3.5 The UMSs were left in place for 3 weeks and the results aggregated for the corresponding 15 minute period for each day.

3.6 The UMSs are installed at suitable sites to provide security, power, and telephone line access. UMS field strength thresholds were chosen to provide coverage of London whilst minimising overlap. Site details are given in Table 1 and the colour prediction chart on Page 9 shows the theoretical coverage of each site.

3.7 Non - overlapping coverage is based on a minimum field strength of 25dBuV/m at each monitoring site. It is clear that some users will be operating with signals below this threshold.

3.8 It can be seen from the coverage chart that a few pockets within London have not been monitored; alternative sites that offered the security and other necessary facilities could not improve the situation. The sites chosen were generally free of in-band transmitters, which would raise the noise floor to unacceptable levels. All channels in sub bands 1 & 2 of Band III were monitored covering both base and mobile legs.

3.9 Each channel in sub bands 1 and 2 has been monitored from each location, and detailed plots of activity have been produced. To keep this Report manageable, plots for two locations only are included - the one with the highest peak loading and the one with the lowest loading. The plots for each location are available for inspection, if required.

3.10 Careful comparison of the detailed plots and the licence statistics build up identifiable profiles matched to particular user groups. The profiles have become an important measure in the Agency’s work towards defining quality of service expectations for a channel.

3.11 The occupancy categories have been chosen to indicate the variation of occupancy levels across channels in a particular group.

4.1 This section of the Report contains details of overall channel occupancy based on the licensing and monitoring information obtained through the survey. It also contains samples of an analysis of individual channels in sub bands 1 and 2 of Band III. The channels are segmented as follows:

4.2 An individual channel analysis of all channels in the two sub bands is produced in full in Parts II and III of this Report.

Part 1: Audit of Land Mobile Radio Use in Sub Bands 1 and 2 of Band III in the London Area (Overview)

Part 2: Audit of Land Mobile Radio Use in Sub Bands 1 and 2 of Band III in the London Area (Individual Channel Analysis)

Part 3: Audit of Land Mobile Radio Use in Sub Bands 1 and 2 of Band III in the London Area (Individual Channel Analysis)

As this report is very large it is not available on-line, copies can be obtained by contacting:

Sub Band 2

Description of Channels	Number
Public Access Mobile Radio channels	401
National channels	95
Unallocated channels	7
Total channels	503
Total spectrum (1006 x 12.5 kHz) = 12.575 MHz

Site No.	Site Name
1	Banstead
2	Heathrow
3	Blackfriars
4	Lippitts Hill
5	Romford
6	Stanmore
7	Sydenham

Audit of Land Mobile Radio Use in Sub Bands 1 and 2 of Band III in the London Area

PART 1

March 2000