 for generating the Rel99 traffic where multiple packet-witched RABs are available for transmitting the data. When no traffic separation is applied in the lub interface, Re199 and HSDPA traffic are sharing one common ATM CBR VP, where the AAL2 priority is applied which assigns higher priority to Re199 traffic over the HSPA traffic. While in the case of using traffic separation, two ATM VPs are established: the transport of Rel99 traffic is over one ATM CBR VP and the transport of HSDPA traffic is on an ATM UBR+ VP. Here UBR+ VP is set to low priority. The following metrics are used for performance evaluation: Application Throughput: the average throughput of transferring a web page at the application layer, excluding the reading time period. Throughput indicates the transaction speed, i.e. how long it takes to transfer a certain amount of data. It is directly related to the application delay and the volume of corresponding data transaction. The normalized application throughput is given in simulation results defined as the ratio of the application throughput under certain lub link bandwidth to the maximum application throughput under an ideal lub capacity. Cell Discard Ratio: in case of congestion of the lub link, the ATM cells are discarded. The packet discard ratio is measured as the ratio of discarded ATM cells to the total ATM cells sent to the lub link. TCP Retransmission Counts: the total number of TCP retransmissions. Link Utilization: the lub link throughput over the given lub link bandwidth. The link throughput includes transport network overheads as well as all TCP/RLC retransmissions. Appendix Impact of Traffic Separation In this section, the influence of traffic separation (TS) is investigated by comparing to the scenario without traffic separation technique in use in the transport network. In this example, there is in average 815.9kbps HSDPA traffic and 968.7kbps Rel99 packet-switched traffic on the lub link. In both with and without traffic separation cases, the offered HSDPA and Rel99 traffic is fi