methodology is based on the processor sharing model. This thesis extends the processor sharing model in order to take into account specifics of the UMTS features and X. Li, Radio Access Network Dimensioning for 3G UMTS, DOI 10.1007/978-3-8348-8111-3_6, Vieweg+Teubner Verlag | Springer Fachmedien Wiesbaden GmbH 2011 6 Dimensioning for Single ATM-Based lub resource management functions, and also consider the case of mixing with circuit-switched type of traffic. To dimension the lub link for satisfying the network-relevant QoS, e.g. packet delay or packet loss ratio on the lub interface, queuing models are proposed to estimate the network performances. In this thesis, two arrival process models are presented to capture the characteristics of the aggregated traffic at the packet level on the lub link. By solving the closed form of delay distributions of analytical queuing models, relevant network performances can be estimated and thus can be used for dimensioning process. 6.2 Dimensioning for Circuit-Switched Traffic For dimensioning process in the framework of this thesis, the considered relevant user QoS criterion for the circuit-switched type of traffic is call blocking probability as a result of Connection Admission Control (CAC). Each connection requires a certain bandwidth in order to achieve the desired quality of service. TNL CAC, as introduced in section 3.3.4.3, is used to decide whether there are sufficient free resources on the transport link (i.e. lub link) to allow a new connection. A connection can only be accepted if adequate resources are available to establish the connection with the agreed QoS while the quality of service of the existing connections in the network must not be decreased by the new connection, i.e. the available bandwidth on the link needs to be larger than or equal to the requested bandwidth of the new connection. In this way, the lub link can only carry a maximum number of simultaneous connections (trunks) each occupying a certain bandwidth which is reserved for those connections. 