oS on the backbone link. The presented network dimensioning approach is twofold: (1) on each last mile link the desired CAC connection reject ratio can be guaranteed; (2) the backbone link can be properly overbooked by considering possible multiplexing gain from aggregating the traffic from all last mile links; while guaranteeing the strict packet delay and packet loss QoS of the lub interface to avoid unsatisfied degradation of end user performances. 8.2 Dimensioning for Circuit-Switched Traffic 8.2.2 Applicability of the Dimensioning Approaches This section presents the results of applying the above proposed analytical approach as shown in Figure 8.1(b) for dimensioning the circuit-switched traffic in a multi-lub RAN. The bandwidth of the last mile link and the backbone link are calculated separately with the MD- Erlang model and MMPP/D/1 model. The main criterion for the applicability of the proposed dimensioning approaches is that, the required connection rejection ratio needs to be guaranteed on the last mile as well as the multiplexing gain needs to be considered on the backbone link and thus overbooking of the backbone link bandwidth can be achieved. For validation of the proposed analytical approach, simulations were carried out to compare with the theoretic expectations. In the presented example scenario, each last mile link generates the same amount of circuit-switched voice traffic a with the same AMR rate peak , and each connection requests the same CAC guaranteed bit rate rm at the last mile. The applied voice traffic model is defined in Table 5.2 with AMR voice codec rate of 12.2 kbps. The following parameters and traffic are configured: Voice traffic per last mile link: a,=19.24 Erlang, peak =12.2 kbps (the AMR codec rate = 12.2kbps), rm =12.4 kbps (the measured average ATM link throughput for the applied voice traffic model is 12.4 kbps, refer to Figure 5.5) Desired CAC connection reject ratio for the last mile link pb=1% Defined packet loss ratio on the backbone link qos b=1% For satisfying the d