8.1.1 Evolution

One of the most dramatic changes in the telecommunications industry over the last few years has been the growth in mobile communications. In the 1980s, mobile communications systems were based on analogue technologies. Several types of system were adopted, based on differing standards, but all were restricted in the variety of services that could be offered and it was difficult to raise the quality of service to meet increasing customer expectations. Mobile stations (handsets) were clumsy and the opportunities for miniaturisation were limited.

In the 1990s, a major transformation took place in which digital technologies were introduced. These technologies overcame many of the limitations of their analogue predecessors. It is now possible to offer a wide range of services at a suitable quality level. Digital technologies applied to mobile stations have allowed wholesale reduction in size and evolving battery technologies have assisted this trend.

The aim of mobile communications systems is to offer services to customers wherever the customers are located. This requires the provision of radio spectrum over the geographic area to be covered. Terrestrial mobile systems aim to achieve this target by providing a network of radio stations. Such systems are termed 'public land mobile networks' (PLMN)1. Coverage for PLMNs is typically 95% to 98% of the population in mature networks. The areas that remain uncovered are in terrain that is difficult to cover economically, e.g. in valleys, and many of these areas are unlikely to receive service.

Satellite technologies are also evolving and...