 sensitive services, and non real time (NRT) which is for the non delay sensitive services. Between them a strict priority scheduler is applied: the RT traffic is given higher priority over the NRT traffic. A.14 Processor Sharing among Multiple RABs A.13 Impact of TCP Slow Start At first, the impact of TCP slow start is investigated with simulations as shown in Figure A.12. It presents the achieved bandwidth utilization efficiency of individual flows as function of file size, with RAB 64 kbps, 128 kbps and 384 kbps, respectively. The bandwidth utilization efficiency is calculated as the achieved mean rate as a ratio to the offered peak data rate. File Size (kbytes) 128kbps 64kbps 384kbps Figure A.12: Bandwidth utilization efficiency over file sizes It can be seen that in general the bandwidth utilization increases with file size. The underutilization of the available bandwidth is due to the TCP slow start at the beginning of the transmission. This underutilization of the available bandwidth is vanishing in case of large file sizes. But for smaller file sizes, especially with web traffic those sizes in the range of 50 kbyte or less, the offered bandwidth cannot be efficiently utilized. It is also noticed that there is a drop for the file size between 1 MSS (here 1460 byte) and 2 MSS, because after the first MSS a secondary IP packet is necessary for transferring the rest of the data, which increases the transfer time by a full RTT cycle. Furthermore, due to the impact of TCP, the relationship between file size and link utilization is non-linear. And it is dependent on the corresponding bearer rate. The lower the radio access bearer rate, the better the bandwidth is utilized. For higher bearer rates, larger file sizes are required to achieve a good utilization of the available bandwidth. A.14 Processor Sharing among Multiple RABs Different RAB type traffic dynamically competes for the network resources. Usually higher peak-rate traffic contends more bandwidth before entering the fair capacity sharing phase. Figure 