- •47 Cellular radio systems
- •47.1 Introduction
- •47.2 Principles of operation
- •47.2.1 Network configuration
- •47.2.2 Signalling
- •47.2.3 Location registration
- •47.2.4 Call set up
- •47.2.6 Power control
- •47.3 Radio planning
- •47.3.1 Cell repeat patterns
- •47.3.3 Radio propagation
- •47.3.4 Practical radio planning
- •47.3.5 Adding capacity
- •47.4 Overview of systems
- •47.4.1 Amps
- •47.4.2 Tacs
- •47.5 Detailed description of gsm
- •47.5.1 Gsm architecture
- •47.5.2 Air interface
- •47.5.3 Speech coding and channel coding
- •47.5.4 Gsm signalling
- •47.5.5 Security features
- •47.5.6 Gsm services and features
- •47.5.7 Roaming
- •47.6 Services
- •47.6.1 Supplementary services
- •47.6.2 Value added services
- •47.6.3 Data services
- •47.7 Future developments
- •47.7.1 Microcells
- •47.7.2 Intelligent networks
- •47.7.3 Personal communications
- •47.8 Conclusion
47.7.3 Personal communications
The term PCN, Personal Communications Network, is used widely in the UK, whilst PCS, Personal Communications Services is used in the USA. Both aim at the same objective of serving the mass consumer market with mobile communications. The key challenge is to provide a very high capacity network to support a large number of users at low cost. Microcellular techniques will certainly be needed, and in order to keep costs down, the concept of regional service, and local access to the PSTN is being considered. IN techniques may offer personal numbering across a variety of networks.
PCN is dealt with in detail in Chapter 48. The standard in Europe, known as DCS1800 is based on the GSM standard but operating at 1800MHz. There is therefore unlikely to be a significant technical difference between Cellular GSM and PCN, with microcellular techniques being equally applicable to either system.
In the USA, the use of CDMA, code division multiple access, is being trialled for PCS. CDMA works on the principle of transmitting unique (orthogonal) codes to identify different users. Detection of signals is achieved by using correlating receivers such that other users appear as pseudonoise. CDMA thus allows a large number of users to share the same (wideband) radio channel.
There is considerable debate about the advantages and disadvantages of CDMA, in particular how to control near/far user interference; the extent to which this can be achieved is crucial to the ultimate capacity of CDMA. One of the key benefits of CDMA is the potential to share spectrum with other users, for example fixed links, and for this reason it is particularly attractive where additional spectrum for mobile systems cannot be made available.
47.8 Conclusion
Cellular radio is a comparatively young technology. Networks employing analogue systems have developed rapidly and now provide high quality service and excellent coverage in many of the developed countries. Technology developments are now increasing the potential network capacity, reducing the size of mobiles, and bringing advanced features and services to the mobile user. The decade ahead with the opportunity to introduce new digital systems and create a world-wide land mobile standard looks particularly exciting.