by the buffer overflow due to traffic overload, or as the result of a certain packet drop function to avoid long queuing delays and link congestion. As explained in section 3.3.3.4, the packet loss ratio is an important QoS requirement for the lub transport network. It should be controlled to be a reasonably low ratio on the lub interface in order to avoid too many retransmissions that will waste the expensive transport resources and also to protect the end user performance from severe degradation. Link Utilization Link utilization serves as an appropriate link-specific QoS. It is expressed as a percentage of the achieved throughput over the link to the given link bandwidth. It is also known as bandwidth utilization efficiency. In this thesis, the above defined network-relevant QoS are investigated for the UTRAN transport network. In Chapter 6.4, the dimensioning of the lub interface to meet the transport network QoS, such as packet delay or packet loss ratio, is studied. 4.2 Important Issues for UMTS Network Dimensioning Network dimensioning is used to determine the capacities of the links in the network, which is one crucial element of the network design process, of traffic engineering and network planning. Network dimensioning is strongly related to a number of issues such as the given traffic demand of the individual traffic classes, the designed network topology, and a certain routing pattern. This section discusses the important issues from the point of view of the network dimensioning in the network planning process. Figure 4.1 illustrates the dimensioning issues within the context of network design, network management and network operation. The presented procedure generally applies to the planning of a UMTS network. First of all, it is necessary to initially set up a network. Initial network design contains the tasks to analyze the traffic that will be carried by the network, to design the network topology including node placement and link selection, to perform routing in order to find advantageous path p