Traffic engineering provides the basis for analysis and design of telecommunication network to carry a given traffic at a particular loss probability. It provides a means to determine the quantum of common equipments required to provide a particular level of service.
Busy Hour: Continuous 1- hour period lying wholly in the time interval concerned, for which the traffic volume or the number of calls attempts is greatest.
Traffic Intensity: The traffic load on a given network may be on the local switching unit, interoffice trunk lines or other common subsystem. For analytical treatment in this text, all the common sub systems of a telecommunication network are collectively termed as servers. In other publications the term link or Trunk is used. The traffic on the network may then be measured in terms of the occupancy of the servers in the network. Such a measure is called the traffic intensity which is defined as: A = period for which a server is occupied/ Total period of observation
Grade of Service: In loss systems, the traffic carried by the network is generally lower than the actual traffic offered to the network by the subscribers. The overload traffic is rejected and hence it is not carried by the network. The amount of traffic rejected by the network is an index of the quality of the service offered by the network and is termed as grade of service (GOS) and is defined as the ratio of lost traffic to offered traffic. Offered traffic is the product of the average number of calls generated by the users and the average holding time per call. GOS is given by
GOS = A-A0 / A0
Where
A= offered traffic
A0 = carried traffic
A-A0= lost traffic