ermined by the PCR (Peak Cell Rate) and this bandwidth will be reserved for the lub permanently. When a user tries to set up a new transport connection (i.e. AAL2 connection) in the UMTS network, it requires a certain amount of transport bandwidth, at the lub to transfer the user data. In order to ensure that the QoS of the ongoing transmissions of other users are not violated and the new connection can have enough bandwidth for guaranteeing its own QoS requirement, each AAL2 connection should request a certain bandwidth that can satisfy the QoS requested by the user. In this context, it is called CAC guaranteed bit rate. It is a configurable parameter in the system which is vendor specific. Their settings depend on a number of aspects like the applications, the applied traffic models, the QoS requirements, the RAB type, etc. For an efficient utilization of the offered transport bandwidth, the CAC guaranteed bit rate should be optimized for each traffic class and RAB type. A detailed implementation can be referred to section 5.4 The algorithm of the TNL CAC is described in the following. The TNL CAC accumulates the total reserved bandwidth of the current existing transport connections, named Total Reserved Bandwidth. When the new transport connection is requested to enter the network, the TNL CAC compares if the sum of the Total Reserved Bandwidth and the CAC guaranteed bit rate of the new connection is larger than the offered lub bandwidth. If so, that means, there is not enough free bandwidth on the lub link to set up this new transport connection offering the agreed QoS, this connection has to be rejected by the TNL CAC. Otherwise, this new transport connection will be accepted by the system as there is still sufficient bandwidth to provide for this new connection. In this case, the new connection can be established and the TNL CAC needs to update the Total Reserved Bandwidth by adding the allocated bandwidth for the new connection, i.e. the CAC guaranteed bit rate. When a transport connection is terminated, i