Congestion Control in WCDMA with Respect to Different Service Classes

In the Universal Mobile Telecommunications System (UMTS) the radio resource management functions are jointly handled in two different protocol layers, the Radio Resource Control (RRC) and the Medium Access Control (MAC). Congestion control functions are performed in the RRC layer. Therefore congestion control requires strong interactions between the radio interface protocol layers, including measurement reports which are transmitted, as well as reconfiguration procedures. In a simulation environment different radio resource reconfiguration procedures are evaluated for congestion control. One aspect is the method which is used to detect congestion. The system performance is presented for a mix of traffic with different service classes. It is demonstrated how during a congestion, different service classes can be differentiated. This provides improved quality of service provisioning for the users according to their service requirements. By choosing the best congestion indicator, a good trade-off can be found between quick congestion resolution and quality of service control on one hand, and efficient utilization of the radio resources on the other hand.