propose required extensions on both models to consider the IP transport specific protocols, functions, and applied DiffServ QoS scheme. In addition, investigations are done to compare the IP-based with the ATM-based UTRAN. Section 7.4 presents main conclusions of these comparisons and a few examples. More results can be found in [LC*07] and Appendix A.22. X. Li, Radio Access Network Dimensioning for 3G UMTS, DOI 10.1007/978-3-8348-8111-3 7, C Vieweg+Teubner Verlag | Springer Fachmedien Wiesbaden GmbH 2011 7 Dimensioning for Single IP-Based lub 7.2 Dimensioning for Circuit-Switched Traffic Same as in the ATM-based lub, the related QoS criterion for the circuit-switched traffic in the IP-based UTRAN is still the connection reject ratio as a result of Connection Admission Control (CAC). In section 6.2.1 and 6.2.2, Erlang-B formula and multi-dimensional Erlang-B formula are proposed to estimate connection reject ratio (i.e. blocking probability) given a certain offered traffic and link capacity, for single traffic stream and multiple traffic streams scenarios respectively. These two models have been studied for the traditional circuit- switched telecommunication network and in Chapter 6.2 they are applied for dimensioning the lub interface in the ATM-based UTRAN and they have been demonstrated to be accurate dimensioning models for the circuit-switched traffic to satisfy a desired connection reject ratio. In the IP-based lub, the applied CAC function is similar as in the ATM-based lub except that the corresponding transport overheads are different in these two transport networks due to different underlying transport technologies being used. This results in different requirements on the physical link bandwidth. Usually the IP-based lub has more transport overheads due to larger overheads of UDP/IP and layer 2 overheads (e.g. Ethernet). However, this only have impact on the demand of the bandwidth for each connection in the CAC algorithm. To accommodate the increased transport overhead, each connection needs a higher b