dio frames will waste the limited transport resources in the UTRAN and lead to a higher delay and lower QoS for the end user. The main reasons for packet losses on the lub are: (1) the excessively delayed frames that are discarded by the Node B; (2) long queuing delays due to the congestion on the transport link; (3) limited buffer space at the ATM switch. The packet losses on the lub link need to be as low as possible. So in order to reduce the packet losses on the lub interface, the transport resources such as transport link bandwidths, buffer space and network structure need to be properly designed. As mentioned in Chapter 1, the transport resources of the lub links are considerably costly. Therefore, effective bandwidth utilization is directly related to the transport costs. High bandwidth efficiency will significantly reduce the radio access network costs. In summary, the key objective of the transport at the lub interface is to provide transmission in a cost efficient way in terms of high transport efficiency and maximal utilization of the lub bandwidth while guaranteeing stringent requirements on delay, jitter, and loss ratio. For achieving this goal, a proper dimensioning for the lub interface is necessary. 3 UMTS Terrestrial Radio Access Network (UTRAN) 3.3.4 Resource Management In UMTS, the resources on the radio interface as well as the transport network are limited and expensive. In order to achieve an efficient utilization of the resources while at the same time provide guaranteed QoS, a proper resource management is required. The main function of resource management is to (1) allocate, establish/release, modify, maintain, manage and schedule the available resources dynamically for each connection upon their requests and demands; (2) control the total amount of resources according to the available system capacity and protect from overutilization of the resources; (3) provide QoS for various services and traffic types in the network, and guarantee their QoS requirements. Within UTRAN, there are two ma