e shared lub link. In cases where the individual flows are not subject to any bandwidth restrictions, i.e. a single elastic flow is able to fully utilize the total link capacity C in times when no other flow is present in the system (i.e. peak >C), then the M/G/R-PS model is reduced to the simple M/G/1-PS model. In general, the M/G/R-PS model can be understood in such a way that several files that need to be transmitted over the common link are broken into little pieces, i.e. individual IP packets of the different traffic flows, and are processed by the link quasi-simultaneously. In this way, large files do not delay small ones too much. And this brings fairness for transferring different files over the same link. It is important to know that the M/G/R-PS model is insensitive to the service time distribution [Lin99]. Thus, for the lub dimensioning process, elastic traffic is characterized by the parameters flow arrival rate de and mean size of the transferred data le, or by the product of these two values, the average traffic volume ae. The QoS of elastic traffic transmission is specified as application throughput (transaction speed for transmitting a specific amount of data, as seen in section 4.1.2.1). Furthermore, a generic QoS measure, the delay factor, will be introduced in the next section, which can be used to quantify the QoS instead. To apply M/G/R-PS model to derive the average transaction time and its respective throughput or delay factor for the elastic traffic carried on the lub link, assumptions are made: (1) there are no packets losses and thus no resultant TCP retransmissions; (2) the maximum window size of a TCP connection is large enough to cover the respective bandwidth-delay product of the network; (3) the lub interface is the main bottleneck between the two ends of a TCP connection (i.e. between the UE and the data server), which would limit the transmission rate of individual flows. 6.3.5 Basic M/G/R-PS Model Figure 6.17 illustrates the definition of M/G/R-PS model. It is a delay system with