The Radio Spectrum: utilisation and management part 2

1. The Radio Spectrum: utilisation and managementpart 2 Les Barclay

2. Regulations for transmissions form satellites and of the use of the GSO Satellites operate in space, beyond the air-space controlled by individual national administrations. However: - satellites could cause widespread and serious interference to other satellite & terrestrial radio systems, - the GSO is a limited resource There is a need to regulate both GSO & radio characteristics

3. . The ITU Radio Regulations specify the way in which the both the space and earth stations may use the radio spectrum and also regulate the use of positions in the GSO. Use of the spectrum is a matter of national sovereignty, but in accordance with international treaty. However, national authority does not extend to satellite heights! Moreover, communication satellites are owned, in the main, by commercial entities and are launched from facilities only located in a few countries.

4. Transmissions from space stations seem to be difficult to regulate. Little incentive for administrations to devote resources to the coordination of frequencies and orbit positions for space stations since they do not contribute any licence fees.

5. Who is responsible? • the owner of the space station? • the administration of the country from which it was launched? • the country which hosts the control facility? each space station is notified to the ITU by an administration

6. The Radio Regulations require administrations to use established coordination techniques for earth stations and for the GSO or criteria based on PFD and probability estimates based on satellite positions. Operators of satellite networks also need to have assurance that their quality of service will be maintained.

7. recognised spectrum access In the UK there is a procedure for “recognised spectrum access” subject to a fee (corresponding to a licence fee) the administration will undertake to take part in coordination procedures, etc., as if the space station were under the authority of the administration

8. Radio Regulations • Provide World-Wide agreement on the use, coordination and regulation of radio • Contain the International Table of Radio Frequency Allocations

9. 4.1 Member States shall endeavour to limit the number of frequencies and the spectrum used to the minimum essential to provide in a satisfactory manner the necessary services. To that end they shall endeavour to apply the latest technical advances as soon as possible   4.2 … in assigning frequencies to stations which are capable of causing harmful interference to services … of another country, such assignments are to be made in accordance with the Table of Frequency Allocations and other provisions of these Regulations  4.3 Any new assignment or any change of frequency … shall … avoid causing harmful interference …  4.4 … shall not assign to a station any frequency in derogation of either the Table of Frequency Allocations … or other provisions … except on the express condition … shall not cause harmful interference

10. Hierarchy of frequency sharing approaches Frequency block allocations – frequency bands identified in the Radio Regulations for use by one or more radio services; Allotment plans – individual channels in a band allotted to specific countries for use for specific purposes, A-priori frequency assignment plans – where the use of a band is planned as a whole on an agreed uniform basis; Modification procedures – to provide a method of including additional transmitters within an a-priori plan Defining maximum technical parameters, such as radiated power or power flux density Frequency coordination – a proposed new transmitter is notified & agreed by the authorities in other countries which may be affected Technical assessment – perhaps within one country where there is knowledge of existing services Field trials – the use of test transmissions to ensure compatible working

11. A-priori planning • Possible to maximise spectrum use by closely packing the requirements • Less and less likely that a blank portion of the spectrum will be available • Little flexibility for modification or for the introduction of new requirements at a later date

12. The Broadcasting Satellite Service • RR 1.38 defines the (terrestrial) broadcasting service as “transmissions intended for direct reception by the general public”. • RR 1.39 for the broadcasting-satellite service (BSS) is broader, to take account of community antenna receiving systems: “a radiocommunication service in which signals transmitted by space stations are intended for the direct reception of the general public. In the BSS the term “direct reception” shall encompass both individual reception and community reception”.

13. Satellite broadcast reception • RRs 1.129 & 1.130 define: • Individual Reception. “The reception of emissions from a space station in the BSS by simple domestic installations and in particular those possessing small antennas.” • Community Reception. “The reception of emissions from a space station in the BSS by receiving equipment, which in some cases may be complex, and have antennas larger than those used for individual reception, and intended for use by a group of the general public at one location or through a distribution system covering a limited area.”

14. BSS Allocations • The primary BSS allocations have been made at 12 GHz for individual reception (although community reception is not excluded); • Region 1; 11.7 – 12.5 GHz • Region 2; 12.2 – 12.7 GHz • Region 3; 11.7 – 12.2 GHz

15. FREQUENCY ASSIGNMENT PLANNING FOR THE BSS • A priori planning for the BSS in frequency bands shared with other services

16. Stage 1 • Sharing services have “permitted” status in advance of drawing up the plan. Assignments for these services do not get primary status until the assignment plan has been made. • Or: add footnote “in the band 11.7 – 12.5 GHz in Regions 1 and 3, the fixed, fixed-satellite, mobile except aeronautical mobile and broadcasting services, in accordance with their respective allocations, shall not cause harmful interference to broadcasting satellite stations operating in accordance with the provisions of Appendix 30.”

17. Stage 2 • All countries state requirements for number of channels and service area.

18. Stage 3 • Define performance objective for service to end user, with equipment with agreed standards of performance. - expressed in terms of demodulated-signal-to- (noise plus interference) - split between feeder link (up) & BSS link (down) and between noise and interference b) Relate the –3 dB footprint to the service area. - calculate in-beam gain of each satellite transmitting antenna - specify receiving on-beam gain, noise factor, out- of-beam gain roll-off characteristics & cross- polar rejection.

19. Stage 3 (cont) • prepare a matrix of isolation provided by the antennas between every pair of service areas as a function of satellite orbital position. • determine frequency channel arrangement and policy on down-path PFD • select the type of modulation, standard carrier parameters, picture standards, receiver selectivity standards etc. Isolation provided by channel separation can then be calculated.

20. Stage 4 Prepare an assignment plan, assigning channels and orbital locations to all the requirements in such a way that the isolation provided by antennas, plus the isolation provided by channel separation, permits the performance objective to be obtained.

21. Stage 4: - if the assignment is not satisfactory: - Improve the efficiency with which service areas have been coupled with orbital positions and channels, or - Make antenna performance standards more stringent - Make more stringent the minimum requirements for some of the various factors which determine the isolation provided by channel separation, or - Accept worse performance, or • Reduce the requirements - Re-iterate the planning process until a feasible plan is achieved and agreed.

22. Stage 5 Prepare a feeder link plan. The arrangement of channels may be the same as for the down-link plan, but the determination of emission parameters may be more complex. (17.3 – 18.1 GHz Detailed assignment plans for the above bands have been prepared and are in RR App. 30A)

23. Stage 6 3 sets of procedures then required for the operation of the plan: • A procedure for amending the plan, for use when a country’s requirements have changed, but respecting the rights of other countries holding assignments in the plan • A procedure for registering planned assignments to the BSS in the MIFR once they have been brought into service. • A procedure for registering in the MIFR assignments to stations of the other services with nominal equality of allocation, and also BSS assignments which are extra to the plan, subject to the protection of planned assignments.

24. The 1977 BSS Plan • service is to national service areas in almost all cases. - For large countries, a set of assignments was made to each time zone in the country. – 3dB footprint of satellite transmit antenna is the minimum ellipse circumscribing points to be specified at the borders of the country, with a minimum beam diameter of 0.6ºfor small countries. But some use of overspill radiation, in Europe for countries using the same, or closely related, languages, in particular German.

29. The 1977 BSS Plan (cont) b) Picture standards - 625 or 525-line; sound sub-carrier combined with video at baseband, the whole FM on the 12 GHz carrier. c) Service planned for “individual reception” (but performance standards maintained if some countries design networks for “community reception”) d) Polarisation discrimination used – with orthogonal circular polarisations.

30. The 1977 BSS Plan (cont) e) satellites located at least 15º W of meridian which determines the local time for eclipse • assumed that most of the circuit degradations, due to thermal noise, interference, etc., occurred on the down-link path – little margin left for up-link degradations

31. The 1977 BSS Plan (cont) • satellites clustered at orbit points separated by 6º with frequency separation between channel centres of 19.18 MHz • (800 MHz of allocated band divided into 40 channels) • All countries have BSS assignments, & all have equal number of channels • 5 channels per country in 800 MHz. • alternate channels assigned orthogonal polarisations, with overlap of outer parts of emission spectra • The 5 channels assigned to a country (or to a time zone) all have same satellite location, same polarisation and all in either the lower or upper half of the frequency band.

32. The 1977 BSS Plan (cont) h) France: channels 1, 5, 9, 13 & 17; 19º W; RH circ pol Germany: 2, 6, 10, 14 & 18; 19º W; LH circ pol Netherlands: 23, 27, 31, 35 & 39; 19º W; RH circ pol UK: 4, 8, 12 & 16; 31º W; RH circ pol peak frequency deviation - 12 MHz; necessary bandwidth - 27 MHz. • User’s receiving system. G/T = 6dB/K; -3dB beamwidth = 2º j) Satellite transmitting antenna gain corresponding to an elliptical beam with a –3dB footprint which circumscribes the geographical points which define the service area or a 0.6º beam, whichever is broader

33. The 1977 BSS Plan (cont) k) Satellite station keeping: E/W; ±0.1º; N/S; ±0.1º beam pointing accuracy; 0.1º of nominal rotation of non-circular beams (due to yaw) <2º l) Emission parameters. • Pfd, edge of coverage (99% of worst month) -103 dBW/m² • Down-link C/N ratio 14dB, including 0.5 dB due to up-link thermal noise (plus interference) • Down-link C/l ratio: co-channel 31dB; adjacent chan. 15 dB m) Entry into force; 1 January 1979 n) revision; plan & associated provisions “have been prepared in order to meet the requirements of the BSS in the bands concerned for a period of at least 15 years from the date of the entry into force of these Final Acts. In any event, the provisions and the associated plan shall remain in force until their revision by a competent administrative radio conference convened in accordance with the relevant provisions of the Convention in force.”

34. The 1977 BSS Plan (results) Plan undermined by: • improvements in receiver technology (lower noise factor, smaller dishes) - competitive services in adjacent FSS bands - new countries - inadequate number of channels New plan and procedure agreed at WRC 2000

35. Unwanted Satellites • old satellites, no longer in use and no longer controllable, may drift around the GSO and interfere with working satellites. - risk of physical collision - interference from an idle satellite emitting telemetry and transponders • RR 22.1 “Space stations shall be fitted with devices to ensure immediate cessation of their radio emissions by telecommand, whenever such cessation is required under the provisions of these Regulations”

36. coordination • a priori planning - limited - where all requirements can be specified in advance, & where an allocated band is available. Maybe ineffective & inefficient for incorporating change. • progressive methods for incremental planning new stations as needed have become much more common. • new stations have to be planned to meet sharing limits, or have to be coordinated with existing services

37. Fixed Satellite Service (FSS) • subject to a greater degree of international regulation than any other service • potentially high quality transmission medium - but wide open to degradation by interference • capable of providing great total capacity, - but may well be insufficient • can by-pass established telecommunications carriers. • How to ensure that all nations have equitable treatment for national satellite systems, - even if they do not start operating until some time in the future.

38. Frequency Sharing between FSS & FS • Almost all FSS allocations shared with FS with equal status. • At SHF, FS mostly for radio relay chains. • Interference likely to occur between FSS & FS and must be kept acceptably low in level. • Most FSS & FS systems used for telephone services, digital service connections or TV connections, with high quality requirements • Some bands likely to be shared with FS using relays from station-keeping high altitude platforms in the stratosphere (HAPS)

39. Reference Circuits Terrestrial radio relay system may have a few hops covering a total distance of, say, 100 km; or 100 hops covering 1000s of km; Whatever the system, noise in a long connection or the ber, due system degradations and interference must not exceed acceptable limits. Performance and interference of each radio relay hop cannot be determined for that hop or that system alone There is the possibility that the channels may be made part of a much longer end-to-end connection.

40. Hypothetical Reference Circuit Hypothetical Reference Circuit (HRC) for analogue transmission systems Hypothetical Reference Digital Path (HRDP) for digital transmission systems. For radio relay these have a length of 2500 km with various combinations of multiplexing and demultiplexing equipments throughout the length of the system. For satellite, one hop is assumed

41. ·FDM telephony: 1-min mean power, <20% of any month. satellite: - 10000 pW0p ·   radio relay: - 7500 pW0p ·  Digital links as part of an ISDN: <10% of any month satellite: BER of 1 per 107; radio relay: BER of 1 per 106

43. Interference between stations of space & terrestrial services may arise by 4 different modes: • Satellite transmitters interfere with terrestrial station receivers, 2. Terrestrial station transmitters interfere with satellite receivers, 3. Earth station transmitters interfere with terrestrial station receivers, 4. Terrestrial station transmitters interfere with earth station receivers.

47. Mode 1: Sharing constraints on satellite emissions. sharing constraints: maximum values of power flux density, measured in a defined sampling bandwidth, at any point on the Earth’s surface limit varies with frequency and angle of elevation: e.g. - at 4 GHz max. pfd is –142 dB (W/m²) in a 4 kHz band at satellite elevation angle of 30º.

48. Art. 21 Limits (extract)

49. Mode 2: Sharing constraints on terrestrial station emissions. a) eirp of FS & MS stations shall not exceed +55 dBW. b) power input to antenna of FS or MS station shall not exceed +13dBW below 10GHz, or +10dBW above 10GHz c) between 1 & 10 GHz, terrestrial transmitted beams shall be at least 2º off direction of GSO, unless eirp < +35 dBW. Or, eirp shall not exceed +47 dBW in any direction within 0.5º of orbit, limit rising linearly in dB at a rate of 8 dB per º to +55 dBW at 1.5º away from orbit. d) between 10 & 15 GHz, terrestrial transmitted beams shall be at least 1.5 º off direction of GSO unless eirp < +45 dBW.

50. Avoiding the GSO