 last mile link as well as at the backbone link. The dimensioning for the star-structured IP RAN transport network applies the same essential ideas of dimensioning the ATM based multi-lub RAN which are presented in section 8.3.2. That is, for a desired end-to-end delay factor, an appropriate target delay factor needs to be assigned to each last mile link and the backbone link individually, which will be used to determine the necessary bandwidths of the individual links with the proposed processor sharing models. In this thesis, approach (3), which is a general dimensioning solution proposed in section 8.3.2, is demonstrated to dimension the multi-lub IP RAN. And the applied processor sharing models for the IP RAN are based on the ones extended for DiffServ for a single link presented in section 7.3.1. The complete dimensioning approach is shown in Figure 8.13. The applicability of this dimensioning 8.5 Overbooking of the lub Backbone Link approach is demonstrated through simulations. The presented results show that the proposed analytical dimensioning approach can be applied well for dimensioning the individual links for elastic traffic in the multi-lub IP RAN, and moreover it can calculate a factor for efficient overbooking on the backbone link. 8.5 Overbooking of the Iub Backbone Link After presenting the dimensioning approaches for the multi-lub RAN networks for both ATM and IP transport, this section will investigate the overbooking, i.e. to derive an efficient and optimum overbooking for the lub backbone link, given a fixed load and last mile link capacity per Node B and a number of Node Bs in the UTRAN (see detailed introduction in section 8.1.2). In this section, the proposed analytical dimensioning approaches, which are presented in the preceding sections for dimensioning the multi-lub RAN for different types of traffic and transport networks, are applied to analytically estimate an optimum overbooking factor for dimensioning the backbone link to meet the user-relevant QoS targets. The calculated overbook