8.1 Introduction

Given the impact of network performance on the QoS perceived by end customers and its role as a platform for the provision of services, it is necessary to understand how the network is likely to evolve in terms of technology and architecture.

Telecommunications networks have been continuously evolving since their inception and exhibit the classical life cycles generally attributed to consumer products. For the market life cycle, a new product will exhibit a growth of sales until market saturation after which sales decline because the market is fully penetrated or is overtaken by a better product. A telecommunication example is the Telex network service. Early growth is often influenced by the need to establish the network platform necessary to launch new network services, that is, technology push. Once critical mass is achieved by the uptake of new network services, then market pull dictates the rate of penetration of the service and is the dominant driver influencing the penetration of technology. The decline phase is determined by obsolescence where a more cost-effective technology with improved service potential becomes available. For obvious reasons all life cycles must overlap.

Application of the network life cycle analogy to the historic development of the network, its current phase of modernisation by digital technology and possible future evolution is shown in Figure 8.1. The timing of the life cycles are relevant to the BT network and will vary for networks of other telecommunications operators depending on market and political influences and technical competence, but...