dth dimensioning, according to the dimensioning procedure described in section 4.3 the link capacity will be adjusted until its resulting connection reject ratio reaches the desired value Pb. At the end, the link capacity which meets the desired target is given to Cac_i* 8 Dimensioning for Multi-Iub RAN Scenario Node B Cac_1 MD-Erlang Model Cac_1, Y1 variation TNL overhead peak Node B correlation MMPP/D/1 switch/router qosbb MD-Erlang Model Cac_n yn Node B (a) Network scenario (b) Analytical dimensioning approach Figure 8.1: Dimensioning for circuit-switched traffic in a multi-lub RAN: with MD-Erlang model for the last mile and MMPP/D/1 model for the backbone link For the backbone link, the dimensioning is aimed to fulfill the transport network QoS requirements and the MMPP/D/1queuing model is applied to derive the required backbone link bandwidth. The dimensioning for the backbone link takes into account the aggregated traffic on the backbone link, which is the sum of the carried traffic (the traffic admitted by the CAC) from all last mile links. The carried traffic on each last mile link y is a result of the CAC. It is calculated as = according to equation (6.7) where the dimensioned last mile link meets the target connection reject ratio Pb. In addition, the transport network layer overhead (TNL overhead) and the user peak data rate peak need to be considered for estimating the total bit rate transmitted on the backbone link. For characterizing the aggregated traffic to be modeled by the MMPP arrival process, the variation and the correlation of the aggregated traffic need to be measured and given as the input parameters of the queuing model as well. With the proper estimation of the aggregated traffic over the backbone link, for a given a link capacity the resultant packet loss ratio can be calculated from the MMPP/D/1 queuing model (see section 6.4.3.2). Then using the dimensioning process described in section 4.3, the optimum backbone link capacity can be determined which satisfies the desired packet loss Q