e link) and fbb (for the backbone link). For each link, given the amount of the offered traffic for that link and the assigned target delay factor, the required minimum link capacity can be calculated with the proposed M/G/R-PS models applied in the single lub link scenarios in Chapter 6.3. For different UMTS network and traffic configurations, various extensions and adjustments to the basic M/G/R-PS model have been proposed in section 6.3.7 for the ATM-based lub interface. These proposed extensions can be applied as well in the multi-lub network scenarios for estimating the individual link capacities, given certain network and user configurations. For instance, when the UTRAN transport network does not apply CAC for the elastic traffic and each user is assigned to the same RAB rate which is fixed throughout the data transmission, then the required minimum capacity of the individual links can be obtained by resolving equation (6.26) and (6.27) iteratively to get the desired bandwidth. In case that multiple RABs are used in parallel, the required link bandwidth can be estimated based on the delay estimation model proposed in section 6.3.7.3. In case of a mixed traffic scenario (elastic traffic mixed with circuit-switched traffic), the solutions suggested in section 6.3.7.5 can be applied to calculate required bandwidth for each individual link in the multi-lub RAN network. 8 Dimensioning for Multi-lub RAN Scenario lub Transport Network lub Transport Network Node B C 'ac_1 PS Model Cac_1 Cac_2 Node B fac_1 PS Model switch/router Cac_n PS Model Cac_n Node B fac_n (a) Network Scenario (b) Analytical Approach Figure 8.8: Dimensioning for elastic traffic in a multi-lub ATM RAN: with processor sharing model for both last mile and the backbone link As additional remarks, the above introduced three approaches to assign target delay factors for the individual links can be applied as well in a general multi-lub RAN, where per lub there are multiple concatenated links along the transport path to connect the RNC and the Node 