Model-­driven maintenance of QoS characteristics in heterogeneous networks

System QoS maintenance is the activity intended to maintain the system QoS at acceptable levels. The activity consists of continuously measuring the system QoS characteristics and adjusting the system parameters that affect them. This paper introduces a model-driven approach to the maintenance of QoS characteristics in heterogeneous networks that support geographically distributed processing services. The model is used as an on-line tool that enables network managers to rapidly adjust the network parameters to maintain the network QoS characteristics at required levels. The on-line use of the model requires short model evaluation times, which are obtained by use of a multi-level hierarchical hybrid technique. The application to the maintenance of timerelated and capacity-related network QoS characteristics is illustrated.