Sunday 5 February 2012

Contents of module

Radio Regulations

The ITU’s Radio Regulations (RR) are the primary reference point for all regulators of spectrum management, and are derived from the recommendations of the World Radio Conference (WRC) and the Regional Radiocommunication Conferences (RRCs). Part 2 examined the division of the spectrum into frequency bands and the use of spectrum among different radio services. Part 3 examines the allocation of frequencies among radio services.

Fixed Service frequency allocations

FS frequency allocations are extensive, but are all shared. Between 30 – 1000 MHz allocations to FS with primary status accounts for 90 per cent of spectrum in Region 3, and around 45 per cent in Regions 1 and 2.

In Region 3 FS is mostly shared with MS and BS, along with other services. Above 1 GHz around 55 – 60 per cent of all spectrum is allocated to FS with primary status, but shared with BS, BSS, FSS, MS, MSS, RLS, SR and ISS. The ability to re-use frequencies varies according to service types, for example, FSS may be highly directional leaving space for simultaneous terrestrial FS use.

Broadcasting Service frequency allocations

WARC allocations of HF spectrum up to the year 2007 provides for 3715 kHz of exclusive bandwidth distributed between the 5950 kHz – 21850 kHz bands, although country variations allow for some sharing with low-powered FS. Both FS and MS services had to shifted to clear these bands.

For wide-area continuous sound and television broadcasting much greater bandwidth is required, up to 80 MHz per TV programme and 2 MHz per audio radio broadcast. In the VHF and UHF bands about 60 per cent of all the spectrum below 960 MHz is allocated to BS, a total of 674 MHz of bandwidth in Region 3 where BS is shared equally with FS and MS.

Above 1 GHz various world and regional allocations have been made. In Region 3 11.7 – 12.5 GHz was allocated to BS on a primary shared basis. BSS allocations have been made near the 12 GHz band and the 40.5 – 42.5 GHz and 84-86 GHz bands.

Digital television and audio broadcasting

The introduction of digital television is subject to the ITU-R Digital television terrestrial broadcasting 1997 Recommendation (BT.798-1) guidelines which propose digital systems should fit into one of the existing 6, 7 or 8 MHz analogue channels.

As the migration towards digital television gathers pace, and that depends upon television industry standards and the pace of technological development and the rate of take-up of digital TV sets by the general public, so more channels will become available for broadcast. But also bandwidth may be freed up from BS for other uses. Digital broadcasts may also migrate to cable systems, or to BSS systems, which would free up yet more sprectrum in the VHF and UHF bands.

In the case of Hong Kong, although digital television broadcasts are expected to commence sometime around 2002, there will be no predetermined cut-off date for analogue broadcasts as the rate of take-up of digital broadcast reception by the public is unknown. When around 50 per cent of households are thought to be receiving television by digital transmission or when the simultaneous transmission of analogue and digital TV signals has commenced for 5 years the situation is to be reviewed.

Sound radio broadcasts using frequency modulation (FM) almost invariably use the VHF band around 100 MHz (87 MHz – 108 MHz in Region 3) which provides better quality than amplitude modulation (AM) at lower MF frequencies for receivers at domestic fixed locations, although FM fades more quickly and is less reliable for moving vehicles.

Digital audio broadcasting systems would offer improvements in quality of reception and will use less transmission power, but it will be some time before digital radio receivers become low cost enough for the general public to accept a switch-over. So unlike the shift to digital television, which has been time-tabled in many countries even though a cut-off date for analogue broadcasts may not always have been determined, for example in the case of Hong Kong, it is unlikely that regulations will mandate digital radio for any time soon.

But satellite digital audio broadcasting (S-DAB) for reception by vehicles and mobile handsets is finding a market. The 1452 – 1492 MHz band has been allocated for BSS for S-DAB outside the USA and one or two other countries, but it is shared with FS and other services. The ITU has also proposed reserving part of the corresponding frequencies of the BS band for terrestrial digital audio broadcasting (T-DAB).

Mobile Services frequency allocations

Mobile services cover land, sea and air. Below 30 MHz maritime and aeronautical mobile services, including satellite, have primary and often exclusive status. In the case of Hong Kong maritime mobile services have exclusivity ranging between 14 and 70 kHz and aeronautical mobile services exclusivity in different bands ranging between 2850 kHz and 137 MHz.

Above 30 MHz, in the VHF and UHF bands, many land mobile service (LMS) devices, such as cordless telephones, remote controllers and security alarms are permitted unlicensed usage of frequency bands a few hundred kHz wide, subject to low power output which will travel only short distances. This allows widespread geographical re-use of these channels. LMS all have secondary and shared status. Citizen Band (CB) is also found in these frequencies.

Although WRC recommendations allow for MS and LMS below 30 MHz, which include primary status in some frequency allocations, they are all shared, and in Hong Kong there are none.

Above 30 MHz both public mobile radio service (PMRS) and private mobile radio services (PMR) are common, but many are secondary and mostly shared with FS, which is often primary. However, there is growing trend along the 30 to 960 MHz spectrum and upwards towards 3 GHz for MS and LMS to replace FS where the latter moves off-air and online.

Private mobile systems are widely used by different industries, typically using a band 20 to 40 MHz wide, divided into uplink and downlink bands, each sub-divided into 12.5 to 25 kHz channels. Users, such as trucking companies, will purchase transmitter/receiving equipment, mostly FM and increasingly digital, tuned to the pair of frequencies assigned to them.

  1. Private Mobile Services
    The demand for PMR is usually very high, and grows in parallel with commercial development as transportation companies enlarge their fleets to cater for growth in freight and passenger traffic. Withers (1999)4 outlines four approaches open to regulators to minimize channel interference:
    1. Same channel-pair assignment may be possible if the base stations are sufficiently far apart, given the frequencies used, height of antennas and nature of terrain.
    2. Ensuring the use of narrow bandwidth equipment, which can be encouraged by pricing the use of spectrum.
    3. Channel sharing can be possible using selective calling devices which can detect when neighbouring networks are not utilizing channels, which happens if different networks have markedly different utilization rates, or use their systems at different times of the day.
    4. Sharing channels can work even during periods of heavy traffic on neigbouring networks if a trunking system is used, which allows any group to seize any channels available on the networks involved. Trunking systems are generally more expensive than simple PMR systems, but make much more efficient use of spectrum. They can work either off a centralized base station system that assigns channels to a group according to immediately availability, or without a base station as mobile-to-mobile. The typical range of transmission is up to 10 km operating at around 900 MHz.
  2. Public Mobile Radio Services

    The public mobile radio system (PMRS) is virtually an extension of the PSTN. First generation (1G) mobile was an analogue system, introduced into Hong Kong in 1985. Second generation (2G) mobile came to Hong Kong during the 1990s, and by 1995 there were three 2G operators who replaced the AMPS 800, TACS 900, and TDMA ETACS networks with D-AMPS, CDMA , D-TDMA and and GSM systems. The D-AMPS system has since been replaced by a narrowband CDMA network.

    In 1996 six Personal Communications Network (PCN) licences were issued for GSM 1800, bringing the total of networks to eleven, operated by six companies. Three of these operators are able to offer seamless handover between their GSM or CDMA territory-wide coverage and their PCN pico-cell coverage of the busiest commercial districts.

    These operators are preparing for 2.5G packet-switched networking, and at the time of writing are awaiting the outcome of the regulator’s decision on the issuing of third generation (3G) mobile UMTS licences. 140 MHz of spectrum is to be allocated during 2001, with the possibility of a further 160 MHz becoming available after three to four years, following the WRC recommendation in May 2000.

    Other common MS services include paging, typically operating around 172 MHz or 280 MHz using assignments of 25 kHz, and cordless telephone and office systems linking work stations operating in frequency bands from around 2 MHz to 2 GHz.

    The key difference here is between licensed and non-licensed uses of frequency, where unlicensed usage is regulated through equipment approval procedures to ensure the devices conform to regulations governing power levels and operating frequencies. Licensed services, on the other hand, are, in the case of Hong Kong, a major source of revenue to fund the work of the regulator’s office, the Office of the Telecommunications Authority (OFTA). This is examined in Part 6.
  3. Fixed Satellite Services

    Fixed satellite services occupy around 55 per cent of WRC allocations of spectrum between 2.5 and 31 GHz. The major services include commercial C, Ku and Ka band GeosStationary Oorbit (GSO) satellite networks services, non-GSO satellite networks services, BBS and MSS feeder links, among others. The higher frequency bands are listed below.
Code Nominal Frequency
range (GHz)
L 1-2
S 2-3
C 4-6 3-8
Ku 10-15
Ka 17-31

Worldwide allocations for FSS are for uplinks, 13.75 to 14.5 GHz, and for downlinks, 10.95 to 11.2 GHz and 11.45 to 11.7 GHz, plus 12.2 to 12.75 GHz for Region 3, mostly using bandwidths of 500 MHz.

The uplinking bands tend to be exclusive, and downlinking bands not used for terrestrial services, although in Region 3 BSS shares with over 12.2 to 12.75 GHz.

FSS shares the 13.75 to 14.5 GHz band with RLS and RN services which are primary.

To avoid undue interference, satellites are expected to be operational within a tolerance of ±2° of their nominal orbital position, and preferably ±5°.

WARC Orb-88 aimed to meet the concerns of developing countries by giving all ITU Member States 800 MHz transmission bandwidth for GSO satellites, using 4500 to 4800 MHz (downlinks) and 6750 to 7025 MHz (uplinks) in the C-band and 10.7 to 10.95 GHz and 11.2 to 11.45 GHz (downlinks) and 12.75 to 13.25 GHz (uplinks) in the Ku-band.

The nature of satellite transmission, especially for small countries, involves the possibilities of cross-border over-spill between Member States of the ITU, and it is a condition of ITU membership that this should be avoided if it involves interference. Four factors pose problems for regulators in this area.

  1. The electrical characteristics of transponders, antennas and emissions need to be taken into account when assigning frequency allocations.
  2. Many satellites are uplinked in one jursidiction but downlinked in others.
  3. Uplink and downlink frequencies are almost always closely related which needs to be taken into account when assigning frequencies.
  4. The tuning ranges of the earth station receivers and transmitters may not be as wide as those of the satellite.

Broadcasting Satellite Services frequency allocations

Broadcasting satellite service (BSS) is sometimes known as direct broadcasting satellite (DBS) and needs to be distinguished from direct-to-home satellite television (DTH) which comes under FSS and is probably today the dominant activity of FSS.

Some countries have been more likely to allow DTH broadcasting as it can be required to confine service to the domestic market, whereas DBS by its nature tends to be cross-border, for example, regional in its footprint.

Only one allocation has been internationally agreed for BSS, around 12 GHz, with feeder links at 14 GHz and 17 GHz, and although BSS is primary it is shared with BS, FS and MS which are also primary.

By 2007 additional spectrum around 17 to 22 GHz should be available. Compared with BS terrestrial television broadcasts using around 700 MHz bandwidth, BSS television broadcasts use around 2.5 to 2.6 GHz.

One application of growing importance is the feed of satellite television and broadband Internet streamed video signals to the head-end of terrestrial cable and fixed wireless broadband distribution systems.

By contrast, satellite radio digital audio broadcast (S-DAB) uses around 1.4 GHz, and this is becoming increasingly popular as a means of providing radio signals to moving vehicles.

Mobile Satellite Services frequency allocations

There are six groups of spectrum allocations for MSS, plus some FSS feeder links to MSS, and in recent years direct links between Medium and Low Earth Orbiting satellites (MEOs and LEOs) to connect subscribers across regions and to connect with terrestrial mobile switching centres or Internet eXchanges. Inter-satellite links (ISLs) can also be provided by Inter-satellite service (ISS) frequencies. The six groups are bands for:

  1. Commercial GSOs, embracing MSS, MMSS, AMSS and LMSS, using bands from UHF and above.
  2. Government, including military, networks, using bands from UHF and above.
  3. Non-GSO systems below 1 GHz using narrow bands, mainly so-called ‘Little LEOs’.
  4. Non-GSO systems using major band systems below 3 GHz in UHF, mostly for global mobile personal communications by satellite (GMPCS), including GSOs, MEOs and ‘Big LEOs’.
  5. Nine bands above 40 GHz, offering ‘millimetre-wave’ MSS allocations, but they are not much used at present.
  6. Distress and safety communications in the VHF and UHF bands.
  7. MSS feeder links from stationary earth stations to satellite are assigned as part of FSS.

In recent years the idea of global satellite-based mobile and Internet services has received much publicity, although the commercial viability of some of these projects remains uncertain.5 Regulators have to be able to accommodate the demand for such innovative services, and at the same time remain aware of how far the market is developing because the spectrum will always have alternative uses and alternative claims made upon it.