What is personal communications? Is it a cellular radio network, some combination of cordless telephones, paging, or a fixed network incorporating Intelligent Network (IN) technology? Rather than defining a technology, personal communications is best described by the features individual users would expect from their 'ideal' personal telecommunications service. Because of this individual nature a single definition is not possible, but the attributes sought by most people can in general be described under a common vision. Personal communication systems aim to provide their users with telecommunications services throughout specified coverage areas. For some users, mobility is the key feature provided by the system, but for mass market acceptability any shortfall in service compared with the fixed PSTN, becomes increasingly important.

Modulation and coding occupy a fundamental place in any mobile or personal communication system. They mediate between the data services, which are to be provided, and the radio systems which form the means of that provision. It is the modulation and coding which determine the quality of the data services, and also how they interact with the radio channel. In particular they determine the resource requirements of the system, in terms of both RF power required and bandwidth occupied. One may regard the encoder/modulator as a single sub-system, which maps data presented to it, by means of a user interface, onto a modulated RF carrier for subsequent processing, amplification and transmission, by the RF sub-system. The demodulator/decoder conversely takes the received RF signal and performs the inverse mapping, back to a data stream for onward transmission. This view underlines the importance of the process; it is the encoding and modulation that determines, for example, the bandwidth occupied by the transmitted signal, whilst it is the demodulator/decoder which determines the quality of the resulting data service availability in terms of BER and delay. It also determines the robustness of the system to channel impairments, due both to the RF sub-systems (such as phase noise and non-linearity) and the RF channel (such as multipath dispersion and fading). Thus the correct choice for the modulation/coding scheme is vital to the efficient operation of the whole system.

Radio planning is a key step for cellular network design and implementation. It is a multi-dimensional optimisation exercise based on many constraints, and includes spectrum allocation, traffic forecast and infrastructure investment. The planning is expected to meet a number of criteria, including a high user capacity, large coverage area, a high quality of service and a minimum quantity of network elements. Radio planning is dependent on many factors, such as the multiple access technique adopted by the system, regulatory and environmental constraints and user behaviour. In general, the overall objective is to provide a large coverage footprint and high user capacity.

The UK cellular marketplace is the most de-regulated and buoyant telecommunications market in Europe, enjoying a significant share of the total European market. Cellnet was formed in 1983 as a joint venture between BT (60%) and Securicor. Cellnet was originally given one of the two licenses issued by the Department of Trade and Industry to operate cellular radio services in the UK, the other being given to Vodafone. As part of that agreement, both companies were assigned 300 radio channels for operation. This was called TACS (Total Access Communications System).

This chapter introduces the concept of mobility by differentiating between different types of mobility a network may provide. It then relates these to the mobility offered in current mobile cellular networks. A brief review of how mobility is managed in these networks is then given and is followed by a discussion of the costs incurred in managing mobility. However, the chapter is chiefly concerned with presenting the findings of studies into mobility management.

Cellular telephony has grown since its inception in the 1980s at a phenomenal rate, with market growth commonly exceeding analysts' predictions. The transition from analogue to the new digital systems has provided further impetus to growth, as has the trend towards smaller, cheaper, personal handsets (replacing earphones as the main product) as well as the increasing regulatory liberalisation of European telecommunications markets. In North America, personal communications services (PCS), based on a range of technologies, are being facilitated, and are seen to represent a major new market over the next few years. It is within such a context that Europe, and the world, are seeking to establish a route towards future so-called third-generation (3G) mobile systems, for introduction early in the 21st Century.

This chapter identifies the particular technical problems and challenges which the successful satellite mobile service must address. Among these are the selection of an appropriate orbit and constellation, the trade-off among modulation and multiple access methods, and frequency reuse strategies to permit a cost-effective service without sacrificing bandwidth. This chapter also considers which of the planned systems has the greatest likelihood of implementation and commercial success.