Basic Elements of Traffic Engineering used in Mobile Networks
In this chapter we shall discuss basic models of systems insingle-service networks. This means that each call always “demands” the same volume of network resources to set up aconnection. An example of a“single-rate network” is, for instance, the “classic” public network, in which each call requires achannel with acapacity of 64 kbps. The models presented apply to planning and dimensioning cellular (mobile) networks of older generations (GSM), which require the same resources for each connection. In particular cases, the models presented can also be used to estimate traffic properties of cells in UMTS and LTE networks.
In mobile networks, the group is understood to be the resources available in one cell of the network. For example, there are 25 channels of 25 kHz each available in acell of aGSM network. Thus, we can consider the cell as afull-availability group with the capacity of 25 channels.
In Sections 5.2 and 5.3, Erlang and Engset models of the full-availability group will be discussed. These models will be presented within acontext of dimensioning hard and soft capacity of cellular networks.
5.2 Erlang Model
5.2.1 Assumptions of the Model
Let us consider a full-availability group with the following assumptions:
- capacity of the system is V servers (links, channels), each of which is available for any call if it is not occupied;
- the calls come from an unlimited number of traffic sources ...