Telecom Consultants International UHF2 Band Reversal Study Presented by Dr. Richard Dewey.

Telecom Consultants International

UHF2 Band Reversal StudyUHF2 Band Reversal Study

Presented byPresented by

Dr. Richard DeweyDr. Richard Dewey

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TCI brief from the RATCI brief from the RA

Assess proposed band reversal strategyAssess proposed band reversal strategy Establish mathematical model for strategyEstablish mathematical model for strategy Estimate cost for implementing strategyEstimate cost for implementing strategy

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Mathematical modelMathematical model

REQUIRESREQUIRES– Accurate Rules databaseAccurate Rules database– Engineering procedures for Engineering procedures for

implementing change strategyimplementing change strategy

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Modus OperandiModus Operandi

The proposal suggested using The proposal suggested using Birmingham as a suitable place Birmingham as a suitable place where both communal and single where both communal and single channel sites could be found.channel sites could be found.

In the event the Hog’s Back and In the event the Hog’s Back and Heathrow Airport were usedHeathrow Airport were used

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Hog’s BackHog’s Back

Chosen as typical communal siteChosen as typical communal site Immediately showed deficiencies in Immediately showed deficiencies in

the Rules database. (NGR and the Rules database. (NGR and antenna height anomalies)antenna height anomalies)

Intermodulation Products not Intermodulation Products not excessiveexcessive

UHF2 traffic too light to make useful UHF2 traffic too light to make useful measurementsmeasurements

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Hogs Back Radio SiteHogs Back Radio Site

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HeathrowHeathrow

Site Survey limited to Terminal 3Site Survey limited to Terminal 3 Measurements difficult due to the Measurements difficult due to the

high noise floor and lack of high noise floor and lack of resolution of the spectrum analyserresolution of the spectrum analyser

Off airport monitoring equipment Off airport monitoring equipment gives more accurate resultsgives more accurate results

Rules database inaccuracies notedRules database inaccuracies noted

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Terminal 3 Short Term Car ParkTerminal 3 Short Term Car Park(North Lift Shaft)(North Lift Shaft)

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Existing frequency assignments around Existing frequency assignments around HeathrowHeathrow

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450 460455 465 470

450 460455 465 470

LPD

LPD

E xisting P M R assignm ents

B ase T ransm itte rs E xisting C A A assignm ents

P aging

Simplified UHF2 Spectrum Diagram for Simplified UHF2 Spectrum Diagram for the Heathrow Areathe Heathrow Area

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Free space coupling between stacked Free space coupling between stacked dipolesdipoles

Coupling Loss between Stacked Dipole Antennas

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

45.00

1 5 9 13

17

21

25

29

Distance apart (m)

Att

en

uati

on

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A Possible Solution for difficult A Possible Solution for difficult sitessites

Tx Antenna Rx Antenna

At least 50 metres

This arrangement is temporary for use during the changeover period but could become permanent if the site were to be managed by a third party.

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Interference AnalysisInterference Analysis

An interference analysis was An interference analysis was conducted and the following conducted and the following conclusion reached:conclusion reached:

At least 500 metres separation is At least 500 metres separation is required between sites to minimise required between sites to minimise

the effects of blocking and wideband the effects of blocking and wideband noise causing desensitisationnoise causing desensitisation

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An Automatic means of An Automatic means of Reassigning FrequenciesReassigning Frequencies

Use a relational database such as Use a relational database such as MS AccessMS Access

Filter out all sites greater than Filter out all sites greater than 500m apart500m apart

Isolate whether they are Isolate whether they are communal or single usercommunal or single user

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Automatic ReassignmentAutomatic Reassignment

See example: See example:

Appendix 7 of ReportAppendix 7 of Report

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CONCLUSIONCONCLUSION Despite identified deficiencies in Despite identified deficiencies in

the Rules database . . . . . the Rules database . . . . .

A procedure for automatic frequency A procedure for automatic frequency reassignment has been identified and is reassignment has been identified and is documented in the TCI report.documented in the TCI report.

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Future WorkFuture Work

A pilot project should be commissioned A pilot project should be commissioned to determine the number of licensees to determine the number of licensees who can be reassigned without recourse who can be reassigned without recourse to special measures.to special measures.

Further site work should take place at Further site work should take place at Heathrow to determine the noise floor Heathrow to determine the noise floor so that a viable cost effective so that a viable cost effective changeover strategy can be developed changeover strategy can be developed for the site.for the site.

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Future Work cont.Future Work cont.

The question of who pays for special The question of who pays for special equipment to aid the process should be equipment to aid the process should be addressed.addressed.

A detailed questionnaire should be sent A detailed questionnaire should be sent to licence holders to determine what to licence holders to determine what costs they are going to incur. The costs they are going to incur. The replies will need careful scrutiny as it is replies will need careful scrutiny as it is likely that such costs may be inflated in likely that such costs may be inflated in order to avoid the disruption.order to avoid the disruption.