xed while the common lub link rate is step by step increased. For the configuration with traffic separation, the PCR of CBR VP for transport of the Rel99 traffic is set to 1600kbps, whereas the MDCR of UBR+ VP for transmitting the HSDPA traffic is increased from 0kbps up to 1400kbps which results in the increase of the total lub link bandwidth. Figure A.23 compares the performance difference of using and not using traffic separation. It shows that with the usage of traffic separation technique, the end user application throughput is improved while the cell losses and resultant TCP retransmissions are reduced significantly. The major reason is that traffic separation provides a minimum bandwidth guarantee for HSDPA traffic, thus the HSDPA traffic will get less influence from the Rel99 traffic. Though the link utilization is similar in both scenarios, there is more link load contributed by RLC and TCP retransmissions in the case of no traffic separation. Application Throughput Cell Discard Ratio with TS without TS with TS without TS lub link rate (kbps) lub link rate (kbps) (a) Normalized application throughput (b) Cell discard ratio TCP Retransmission Counts lub Link Utilization with TS without TS with TS without TS lub link rate (kbps) lub link rate (kbps) (c) TCP retransmission counts (d) lub link utilization Figure A.23: Performance comparisons: with TS and without TS A.16 Use of Traffic Separation for Transport of HSPA and Rel99 From these results, we can conclude that to achieve the same application throughput or cell discard ratio target, using traffic separation needs less bandwidth on the lub link, which means a more efficient utilization of the transport resources. For example, to achieve 90% normalized application throughput, applying traffic separation requires 2800kbps while no traffic separation requires 3300kbps on the lub link. The obtained bandwidth saving is 15%. To guarantee less than 1% cell discard ratio, using traffic separation requires minimum 2100kbps bandwidth while no traffic separation r