er distributions and also for web applications. Figure 6.32 shows such a web scenario where the size of a web page is 12 kbyte. For the given two different bearer distributions, the simulated average application delays (i.e. page download delays) over different link utilizations follows approximately the theoretical results derived from the general PS model. Multi RABs, file size=12kbyte, lub=1600kbps, no CAC Multi RABs, file size= 12kbyte, lub=1600kbps, no CAC M/G/R PS M/G/R PS 33.3% PS64 33.3% PS128 30% PS128 50% PS64 Link utilization Link utilization Figure 6.32: Average application delay over the load for multiple RABs with different RAB distributions: web scenario, no CAC, constant page size (12 kbyte) 6 Dimensioning for Single ATM-Based lub These results demonstrate that the average application delay per RAB type can be derived from the proposal general M/G/R-PS mode, taking the total load of all flows into the link congestion while considering specific RAB peak data rate for calculating the transfer delay per RAB type. 6.3.8.5 BRA without Applying CAC With the application of Bit Rate Adaptation (BRA) function, the peak data rate of elastic traffic flows is changed dynamically during data transfer process. The change of peak rates introduces a problem for deriving R for the M/G/R-PS model. To solve this problem, section 6.3.7.4 proposes to derive R based on the mean peak rate peak_avg which is calculated with equation (6.35) given different peak rates and their portions in use over time. In addition, an average around trip time RTT avg is estimated. With peak_avg and RTTavg, the overall average transfer delay or average throughput can be calculated by the M/G/R-PS model. The following presents a scenario with BRA in use. In the given example, web application is chosen with a constant page size of 12 kbyte. The validation results are presented in Figure 6.33. The left diagram plots the calculated average page transfer delays over different loads from the proposed approach. The calculations are compared with 