- The Radiocommunications Act 1992
- International Telecommunication Union
- Radio wave propagation
- Technical planning in Australia
- Radiocommunications standards
- Interference management options
The radio spectrum is a sovereign asset, which in Australia is managed by the Commonwealth Government. The Australian Communications and Media Authority (ACMA) is an independent Statutory Authority within the Commonwealth Government's Communications portfolio and reports directly to the Minister for Broadband, Communications and the Digital Economy.
The ACMA must manage the spectrum in accordance with the Radiocommunications Act 1992 (the Act) which sets out the objectives and the tools available to it. These tools include powers relating to frequency planning, licensing and technical standards. The Act also contains provisions on public consultation and rights of appeal.
Spectrum planning is a multi-faceted activity drawing on the disciplines of engineering, economics and social science. Planning is conducted within an overarching international framework. In most countries, including Australia, planning starts at the international level through participation in the International Telecommunication Union (ITU). The ITU is a technical arm of the United Nations and maintains the international Radio Regulations, which sets out the allocations of various bands to various types of services.
Australia, like many other countries, is a signatory to the ITU Convention. This means that Australia has obligations under international law regarding compliance with the Radio Regulations. In essence, Australia must not cause interference to the services of other countries where those services operate in accordance with the Regulations conversely, Australian services are entitled to protection against interference from other countries only when our services operate in accordance with the Radio Regulations.
The way in which a radio wave propagates depends on its frequency. That is, different frequencies will have different characteristics with regard to how far the radio wave travels, or the degree of penetration through trees or into buildings. The needs of the various types of services are also different. One of the fundamental aims of technical planning is to maximise the use of the spectrum by matching the needs of a service with the appropriate propagation characteristics.
Another consideration is that of equipment cost, which is also often frequency dependent. Generally speaking, cost increases as the frequency increases.
A consequence of the above two factors is that some bands are more valuable and in much higher demand than others.
The Australian Radiofrequency Spectrum Plan
The Australian Radiofrequency Spectrum Plan (ARSP) is the broadest level technical document showing the allocation of bands to various types of services. It is a bit like a town plan subdividing land into zones. As well as giving the first layer of spectrum resource allocation, there is a degree of interference avoidance built into the service allocation relationships and associated regulations.
The ARSP is drawn from, and kept current with, the ITU Radio Regulations, which are revised every few years at World Radiocommunication Conferences.
The ARSP is the first planning document that should be consulted regarding spectrum arrangements in Australia. However, it is just the starting point and is not usually sufficient for assigning specific frequencies to users for frequency co-ordination, two lower levels of planning are usually necessary as described below.
Band plans and channel plans
Band plans and channel plans (eg, Microwave Fixed Services - RALI FX3) take a band of spectrum and provide a more detailed description of how the band is allocated. Band plans provide detailed allocation of the spectrum resource between types of services. They usually contain detailed frequency channelling arrangements and build in a number of specific interference avoidance measures. These plans are developed as and when necessary.
Frequency co-ordination procedures
To avoid interference, radio receivers need to be adequately separated in frequency or in geographic distance from undesired transmissions, or in some combination of both. The frequency/distance separation relationship is dependent on the characteristics of the services concerned and on the propagation characteristics of the frequency band. It is necessary to establish and codify these relationships to enable frequency assignments to be made and interference to be avoided. Documentation for various frequency coordination scenarios is also available on the ACMA website.
Generally, the Act requires that the users of transmitters must be licensed. There are three forms of licences allowed:
- Apparatus licences - specify the category of service, eg, fixed or mobile, and the technical characteristics including the location, power, frequency of operation and the radiofrequency emission type. These licences are usually site-based, usually issued over-the-counter, and represent the majority of our licensing activity. Apparatus licences may be traded. More information on licensing categories and fees is available electronically. An online database of current licensees is also available.
- Spectrum licences - these are area-based licences and are intended to be technology and service neutral to the extent possible (ie, the type of service is not specified) so as to give maximum flexibility to the licensee. Once allocated, these spectrum assets are fully tradeable, and can be sub-divided or amalgamated in either the geographic or the frequency band domain. This allows licensees to acquire, through participation in auctions or through trading in the secondary market, whatever spectrum space is necessary to deploy the type of service required. To support this approach, technical frameworks are established to manage interference across the area and spectrum boundaries of adjacent licensees.
- Class licences - typically, class licences are umbrella licences designed to provide "public parks" for the authorised use of various low powered devices that have a low interference potential. Common examples of these devices are garage door openers, remote car door locks and intruder alarms, wireless microphones, automatic tollway systems and tag security systems. Provided these transmitters comply with the conditions of the class licence, then individual licences are not required.
Radiocommunications standards are developed as necessary to ensure compatibility or to contain emissions from transmitters.
Interference is managed by the combined effects of licensing, regulations, standards and frequency co-ordination procedures. The three forms of licensing described above all manage interference but have different mixes of these essential ingredients. Deciding on the appropriate form of licensing for a particular application is a matter of choosing "horses for courses".