TABLE OF CONTENTS To engineer any telephone system, wireless or landline, we need some way of estimating telephony demand and criteria for satisfying that demand. Traffic engineering is the process of assigning facilities to satisfy a demand. Traffic engineering is particularly important inside the public switched telephone network (PSTN), the Internet, the cellular backhaul network, and other networks where demand from multiple users is carried over shared channels. Statistical methods can be applied to estimate demand and design facilities to meet peak demand. In this chapter we will explain those methods. First, we will look at the methods traditionally used in telephony, which assumed that all circuits were the same size and that the average length of telephone calls was unlikely to change very much. Then we will discuss the implications of data usage and data services and how they require new models. After that, we will discuss the traffic engineering of packet networks.
The most fundamental traffic engineering job in telephony is the assignment of transport facilities to serve fixed-size voice channels. There is a demand of voice telephone calls to be served, some community of subscribers making calls. While telephone usage patterns are not random to the subscribers themselves, so far as the telephone network is concerned, the demand is a random statistical process, a distribution of calls over time.
When each call attempt is made, the telephone network serves the call if it has facilities to do so, or it blocks...
