 dimensioning of the ATM-based lub, this chapter is focused on dimensioning the IP-based lub of a single link. Different than the ATM-based UTRAN, the IP-based UTRAN employs IP as the underlying transport technology and thus has a different protocol stack and transport network. Additionally, it applies IP QoS schemes in the transport network to serve various service classes with different priorities. In the framework of this thesis, the investigated IP-based UTRAN applies the Differentiated Service (DiffServ) QoS scheme and a combined Weighted Fair Queue (WFQ) and Strict Priority (SP) scheduling strategy in the IP transport network, in order to distinguish different service flows and guarantee the desired QoS for various service classes. For dimensioning such an IP-based URRAN, in this chapter analytical models are proposed to determine the required IP bandwidth for the lub link to satisfy user defined QoS of various service classes. Same as for dimensioning the ATM-based lub, two fundamental traffic types are studied: elastic traffic and circuit-switched traffic. Section 7.2 presents analytical dimensioning models for circuit- switched traffic, and section 7.3 proposes analytical dimensioning models for elastic traffic. In section 7.4, the performances of ATM and IP based UTRAN and their required lub link bandwidths are compared. 7.1 Overview and Objectives In this chapter the dimensioning process for the IP-based UTRAN is focused on guaranteeing user-relevant QoS as the main objective of dimensioning. In the framework of this thesis, the considered user QoS for circuit-switched traffic is the connection reject ratio and for elastic traffic it is the end-to-end application throughput or delay (see section 4.1.2.1). For these two QoS targets, the M/G/R-PS models are proposed to dimension for elastic traffic and the Erlang models to dimension for circuit-switched traffic for the ATM-based lub in Chapter 6. This chapter will discuss the applicability of both analytical models for dimensioning the IP-based lub, and 