Historically, radiocommunication has been seen first of all as a solution for the problem of communicating with mobile terminals, particularly with ships at sea, and later as a means of communicating flexibly to long ranges. In these kinds of traditional applications there may be requirements for high reliability and for a specified good quality of service thus requiring good spectrum management techniques and the control of interference. Moreover, since the propagation of radio waves does not cease at national borders, it becomes a matter of international negotiation and regulation. This has led to the establishment of a structure of international treaties and bilateral agreements and to a conservative approach in assessing the probability of interference.
It is interesting to scan the spectrum allocations contained in the Radio Regulations and to see how these have formed to take advantage of the general propagation characteristics of each part of the spectrum, against the constraints of progressively advancing technology and demand.
The spectrum allocation mechanisms have served the international community well and have enabled radiocommunications to develop and to offer new and higher data-rate applications, taking advantage of the progress in the development of technology. However as the radiowave spectrum has become more intensively allocated and occupied, the time taken to achieve agreement, and the complexity of necessary back-up studies, have served to impede the rate of progress which innovators would wish to see.
But many new applications are quite different in character from the traditional uses. There are demands for high data rate, short range communications for business and domestic purposes where a somewhat lower performance is likely to be satisfactory. Modern technology permits intelligent adaptive operation to modify the coding or modulation method or to select an unoccupied frequency channel. For such applications the full rigour of the international agreements may not be appropriate. It may be expected that new and expanded uses for radio will continue to grow, so that good spectrum management will continue to be needed, based on technical considerations, to achieve effective spectrum usage with opportunities for new applications as they are proposed. The use only of a market based approach to spectrum usage will not be suitable for preserving opportunities for the implementation of new applications and will not foster the introduction of embryonic and innovative concepts.
In principle, for such short range applications the choice of frequency range is quite wide. There is a broad balance between the complexity of technology, antenna performance and size, propagation considerations - notably diffraction, and power requirements. The choice needs to take account of existing spectrum users. Tools are needed to evaluate the capacity of the spectrum, to assess the effectiveness of developing applications, and to manage the interference environment.