ser to standardized systems than other chapters in the book. Deeper descriptions of particular access systems can easily be found in the rich literature that is available on the market. 13.2 INTRODUCTION In order to retain a balance between different network segments in this book, there is no point in going too deeply into individual system solutions in such a fragmented area as access has become. The number of parameters includes for example the range of services to be offered, transmission media, availability of frequency bands, the layers above including the signalling system, multiplexing and aggregation technique, subscriber (CPN, Other if any) network Terminal Service network Content Content Applications Service enablers Service enablers (Mobility), QoS, security management Access Access Core connectivity Customer User information flow access unit for fixed and mobile accesses Figure 13.1 Position of the chapter, and the main access internal nodes Understanding Changing Telecommunications - Building a Successful Telecom Business, by A. Olsson © 2003 Ericsson och Student litteratur. ISBN: 0-470-86851-1 Understanding Changing Telecommunications - Building a Successful Telecom Business Services Network sharing? Service network access Control layer point Mobility management, charging, security (management Ex BSC subscriber data Requirements Access Access Backbone transport Access node 2 Revenue Expenses Capital employed Figure 13.2 A broader view of access architecture, environment and issues velocity, variations in business conditions such as ARPU, adaptation to geographical topology and subscriber density, distance to the edge node, cost development and new enabling technologies. The result is thousands of different possible access network designs. Therefore stress is put on the more generic aspects of access, complemented with overview information on some specific systems. In the long run access independence is more or less necessary, and the development is ongoing. A fairly generic access architecture with 