 radio access network and each Node B serves a number of UEs, as shown in Figure 8.4, and that all flows are given the same RAB rate peak Each last mile link has a capacity Cac_i and transmits a certain amount of elastic traffic Pi . The backbone link is assigned with link capacity Cbb. The total amount of elastic traffic traversing the backbone link is the sum of the traffic from all last mile links. Then the end-to- end transaction time T for a file size of X1 is calculated as a function of the requested file size Xt, the assigned RAB rate peak the carried amount of traffic over the last mile link and the backbone link as well as their allocated link capacities, and additionally the TCP RTT if taking into account the impact of the TCP slow start. The following equation (8.2) gives a general function of calculating the end-to-end delay T1 for the ith lub interface: (8.2) The required end-to-end delay QoS requirement can be represented as well by the end-to- end delay factor f. As introduced in Chapter 6.3.5, the delay factor represents the increase of the average transfer time (or decrease of the average throughput) imposed by the congestion (see equation (6.20)). For each last mile link and the backbone link, an individual link delay factor can be calculated. The individual link delay factor indicates the additional delay caused by the congestion of the individual link. fac_i denotes the link delay factor of the last mile link of the ith lub interface and fbb denotes the link delay factor of the backbone link. To estimate the end-to-end delay T1, three basic network cases are considered: The last mile link is configured with a limited capacity that results in fac_i>1, while the backbone link is configured with adequate bandwidth that will not cause any traffic congestion, i.e. fbh=1; The last mile link has a sufficient bandwidth that makes fac_i =1, while the backbone link is set to a limited bandwidth that cause congestion on the backbone link which leads to fbb>1; Both last mile link and the backbone link are