Master's thesis
Introduction
Optimum traffic conditions can be achieved in the Public Land Mobile Network (PLMN)thanks to an increasingly sophisticated range of variations in network design and traffic routing. This involves the increased intermeshing of the network nodes and thus a greater planning effort. Careful, future-oriented planning makes it possible, in the majority of cases, to avoid traffic bottlenecks and overload situations, even in the face of major traffic fluctuations.
Traffic data acquisition is therefore of decisive importance for the telecommunications carriers with respect to
· traffic handling (Traffic bottlenecks can be detected as early as possible.A consistently high quality of service can be ensured, resulting from the grade of service,call processing performance and transmission quality.)
· traffic forecasting (Network nodes can be composed for the long-term, demand-oriented expansion ofthe networks.)
Contrary to the systems of older technology, the D900/D1800/D1900 system does not require any special equipment for traffic data acquisition. A broad range of intra-system functions is available for the tasks at hand. These functions collect and process traffic data from all parts of the network nodes and trunk groups. For instance, the call processing programs include traffic data registration and specific programs record traffic measurement data.
The numerous tasks in traffic data acquisition are subdivided into two areas for the purpose of more convenient management and handling:
– traffic supervision
– traffic measurement
Traffic supervision
Traffic supervision implies that traffic flows, losses in the trunk network, and other variables which affect the quality of service must be determined. To provide the required quality of service, the telecommunications equipment in operation at any time must therefore be supervised, continuously or periodically. Therefore, traffic data for the operation
is recorded and call processing traffic of the network nodes and the switching network is analyzed.
The grade of service is affected by the modes of operation (e.g. a delay or a loss ) associated with the dimensioning of the serving trunk groups. To ensure an adequate grade of service for switching operations in the individual network nodes, software
counts are periodically compared with predefined threshold values. Should these threshold values be exceeded, messages and data indicating any irregularities in call processing are output. A result is, for instance, that faulty trunks (transmission paths)
can be blocked at short notice, or traffic overloads can be anticipated and prevented, e.g. by traffic management measures.
Traffic measurement
Traffic data acquisition is also used to verify whether the traffic data taken as a planning basis is still correct. Therefore, the dimensioning of trunk groups is an important planning task. To ensure sufficient traffic handling capacity, the grade of service in the busy hour is prespecified when trunk groups have to be expanded or added.
Traffic has to be processed not only by trunk groups and switching networks, but also by all the control devices associated with them. It is essential to know how often the devices will be used within a given time. A gauge of this demand is the mean number of
calls offered per unit of time, the number of call attempts during the busy hour (i.e., the BHCA value), the number of successful switching network (SN) through-connections. Measurements of these traffic variables indicate the call load on the call processors and on the control devices, and the requirements for the switching network.
Traffic measurement registers events and duration of states in the system or system parts. Hence, basic data for the long-term expansion of call-processing equipment is available to meet a growth in telecommunications traffic over time. Since the traffic data from the peak traffic periods must be used as the basis for planning work, traffic measurements must be carried out during these periods.
References
1. Siemens AG2001. Traffic and Performance Data. Counter Description. Public Communication Network Group.
2. Faruque, S., Cellular Mobile Systems Engineering, Norwood, MA: Artech House, 1996.
3. Siemens. ATM Traffic Management.
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