The Radio Spectrum: utilisation and management

1. The Radio Spectrum: utilisation and management Les Barclay

2. Information revolution Value of information Demand for bandwidth

3. No shortage of bandwidth Cable and optical fibre systems can have as much bandwidth as they need. Standards and protocols only have to be agreed between those concerned

4. Need for mobility Information is only of value if it can be delivered where it is needed Some mobility through intelligent wired network More mobility through wireless LAN technology, etc

5. But for true mobility Flexibility and rapid deployment Radio is the only option

6. There is only one radio spectrum Capability only expandable to a limited extent into the mm wavebands or by improving modulation and coding methods MUST use it effectively to get best value, and to have potential for future expansion of services

7. Need adequate quality of service Assurance of protection against interference REGULATE

8. National Regulation • Each country is sovereign – can authorise the use of radio transmissions • Needs to plan and control the use of radio • Licensing, etc • In UK: OFCOM • (previously the Radiocommunications Agency)

9. Satellite transmissions • Particular problem as the transmitters are not within the territory of the country

10. Regional • Common objectives to coordinate the use of radio: • To avoid interference • Create common equipment specifications • Permit cross border use • In Europe • European Communications Committee of CEPT • ETSI

11. International • International Telecommunication Union • International treaties to regulate the use of the radio spectrum and the satellite orbits

16. radio spectrum 3 kHz to 3 THz • main use 9 kHz to 400 GHz: • range covered by ITU Radio Regulations.

19. ELF (below 3 kHz) and VLF (3-30 kHz) Typical services: world-wide telegraphy to ships and submarines; time standards; worldwide comms, sub-surface comms System considerations: even largest antennas only a small fraction of a wavelength with low radiation resistance; bandwidth very limited, only low or very low data rates; high atmospheric noise Propagation: In Earth-ionosphere waveguide, relatively stable propagation; asymmetric propagation E/W & W/E. Propagation through sea-water, which has significant skin depth for these wavelengths.  No international frequency allocations below 9 kHz. Limited use below 9 kHz for military purposes.

20. LF (30-300 kHz) Typical services: long-distance shore-to-ship communication; fixed services over continental distances; broadcasting; time signals System considerations: vertical polarisation (for ground wave propagation, & for antenna efficiency); efficient but large antennas possible; directional antennas very large; high atmospheric noise; limited bandwidth. Propagation: up to several thousand km; ground wave, strong sky wave at night, slow fading

21. MF (300 kHz -3 MHz) Typical services: broadcasting; radionavigation; maritime mobile communications; System considerations: 1/4 l vertical antenna at 1 MHz is 75 m high; directional antennas possible, magnetic receiving antennas; Propagation: ground wave more pronounced over sea; strong sky wave absorption during the day, but little absorption at night; high atmospheric noise levels

22. HF ( 3-30 MHz) I Typical services: international broadcasting, national broadcasting in tropical regions; long-distance point-to-point communications; aeronautical and maritime mobile communications; System considerations: arrays of horizontal dipoles; log-periodic antennas (vertical or horizontal), vertical whip antennas; frequency agility essential; crowded spectrum needing good intermodulation performance; external noise environment varies with time and location. Bandwidths up to about 6 kHz

23. HF ( 3-30 MHz) II Propagation: propagation up to world-wide distances by ionospheric sky-wave, very variable in time. Propagation window between MUF and LUF (maximum and lowest usable frequencies) varies from a few MHz to about 20 MHz Comment: necessary to change the operating frequency several times during 24 hours. Broadcasting uses schedule of frequencies. Fixed and some mobile services use intelligent frequency adaptive systems. Continues to provide the main intercontinental air traffic control system. Most modulation bandwidths may exceed the correlation bandwidth.

24. VHF ( 30-300 MHz) I Typical services: land mobile for civil, military and emergency purposes, maritime and aeronautical mobile; sound (FM and DAB) and (outside UK) TV broadcasting (to about 100 km); aeronautical radionavigation and landing systems; cordless telephones; paging; very limited little LEO satellite systems System considerations: multi-element dipole (Yagi) antennas, rod antennas suitable for vehicle mounting, atmospheric noise small but man-made noise significant. Some use for meteor burst communications

25. VHF ( 30-300 MHz) II Propagation: usually by refraction in troposphere; reflections may cause multipath on line-of sight paths; screening by major hills, but diffraction losses generally small; some anomalous propagation due to atmospheric refractivity; unwanted ionospheric modes due to sporadic E and meteor scatter. substantial Faraday rotation and ionospheric scintillation on Earth-space paths

26. UHF (300 MHz - 3 GHz) Typical services: TV broadcasting; cellular and personal communications; satellite mobile; GPS; important radio astronomy bands; surveillance radars; terrestrial point-to-point service; radio fixed access; telemetry; cordless telephones; tropospheric scatter links. System considerations: small rod antennas; multi-element dipole (Yagi) antennas; parabolic dishes for higher frequencies; wide bandwidths available Propagation: : line-of sight and slightly beyond; tropospheric scatter for transhorizon paths, screening by hills, buildings and trees; refraction effects; ducting possible; ionospheric scintillation

27. SHF (3-30 GHz) Typical services: fixed (terrestrial point-to-point up to 155 Mb/s); fixed satellite; radar; satellite television; GSO and NGSO fixed satellite services; remote sensing from satellites; RFA System considerations: high-gain parabolic dishes and horns; waveguides; major inter-service frequency sharing; wide bandwidths Propagation: severe screening; refraction and ducting; scintillation; rain attenuation and scatter increasing above about 10 GHz; atmospheric attenuation above about 15 GHz, ionospheric effects becoming small.

28. EHF (30-300 GHz) Typical services: line-of sight communications, future satellite applications; remote sensing from satellites; MVDS; fixed service in the future using high altitude platforms System considerations: small highly directional antennas; equipment costs increase with frequency; little use at present above 60 GHz; very wide bandwidths; short range Propagation: severe difficulties: screening; atmospheric absorption; rain; fog; scintillation

29. Spectrum Occupancy Space: service range coverage area interference range or area Time: continuous or intermittent transmission propagation variability Bandwidth: necessary bandwidth transmitter and receiver imperfections

31. Spectrum Utilisation (U) U=BxSxT where B is the bandwidth S is the geographic space or volume occupied (desired or denied) T is the time Not a real equation!

32. Geographic space Area coverage systems such as broadcasting or mobile applications: - required space is defined as coverage area Point-to-point communications – desired space is confined to the direct path between the terminals Geostationary satellite networks:- just the orbit spacing around the geostationary arc and the direct links to earth stations

33. Geographic space BUT: More relevant to define spectrum utilisation in terms of the geographic space denied to others Consider: radiated power antenna directivity propagation for small time percentages Passive applications such as radio astronomy, have no transmissions, but still need a large geographic space to give protection against interference

34. Bandwidth for narrow band systems – related to information rate complex modulation methods permit more bits/Hz but usually need a more perfect propagation channel spread spectrum – consider a factor related to the power density across the bandwidth

35. Time factor Unity for broadcasting Smaller for some other applications

36. Efficient spectrum utilisation Perfect technical efficiency would require: Perfect transmitters – no unwanted emissions Perfect receivers – no susceptibility to other signals - perfect selectivity High gain antennas, accurately pointed Emissions limited to the necessary bandwidth Minimum power to provide sufficient signal Maximise frequency reuse etc

37. This would impose impossible demands on equipments - too expensive - unreasonable maintenance - no flexibility for changing requirements

38. Effective spectrum use Seek efficient use within practical constraints Specifications for unwanted emissions reasonable selectivity characteristics Design for acceptable cost Rapid entry to market Provide for future flexibility etc. Effective usage is a more reasonable aim

39. International Telecommunication Union and the Radio Regulations

40. History of International Telecommunciation 1849 first international telegraph 1865 foundation of international telegraph union To deal with emerging technical and financial problems of international telegraphy 1876 invention of telephone 1895 first wireless communication 1906 first international Radio Conference 1927 CCIR established 1932 becomes International Telecommunication Union 1947 becomes specialised agency of the united Nations

41. Purposes of the ITU ITU – concerned with the international regulation of telecommunications Purposes include: To extend international cooperation To offer technical assistance To promote the development of telecommunication facilities and their most efficient operation To this end the ITU,amongst many other things Undertakes studies Adopts recommendations Collects and publishes information

42. The ITU shall Allocate frequency bands, register assignments and geostationary orbit positions to avoid harmful interference Coordinate efforts to avoid harmful interference and improve use of spectrum and GSO Facilitate international standardization Foster international cooperation Harmonise development of facilities Establish rates as low as possible, consistent with efficiency Ensure safety of life Undertake studies

43. Membership of ITU Member States (national administrations) Registered operating agencies Scientific and industrial organisations

44. ITU modernised in 1947 Plenipotentiary Conference - Every 5 years World Adminstrative Radio Conferences (WARC) - Held as required World Administrative Telephone and Telegraph Conferences (WATTC) - infrequent

45. General Secretariat International Frequency Registration Board CCIR secretariat (international radio consultative committee) CCITT secretariat Telecommunication Development Bureau

46. International Frequency Registration Board • Record and register frequency assignments and locations in the GSO • Maintain and publish the Master International Frequency Register • Examine the probability of harmful interference • Advise on spectrum usage • Publish the seasonal HF broadcasting schedule • Undertake inter-sessional work for WARCs • Offer technical assistance • Develop coordination procedures

47. Need for change Perceived pressure from regional standardization bodies budget speed complexity convergence = ITU reorganization

48. WARCs following WARC 1979 1981 W general allocations 1981 R MF BC (region 2) 1983 W mobile 1984 W HFBC 1st session 1984 R VHF BC (reg 1 & part reg 3) 1985 R radiobeacons (Europe) 1985 W VHF/UHF BC (Europe) 1985 W GSO planning 1st session • W HFBC 2nd session • R MFBC (region 2) 1988 W GSO 2nd session 1989 R VHF/UHF TV BC in Africa 1992 W allocations, etc

49. New ITU Plenipotentiary Conference – every 4 years ITU Council – 41 members, meets annually Three Sectors Radiocommunication Telecommunication standardization Telecommunication development Each sector has: study groups, advisory group, and is supported by a Bureau

50. Radiocommunication sector World Radiocommunication Conferences Every 2 years ( now a longer interval) Radiocommunication Assembly To manage the study groups, at the same time ad the WRCs Radiocommunication Advisory Group Meets annually Radio Regulations Baord 9 part time members Radiocommunication Bureau (BR)