on. In general, the M/G/R-PS model is applied when there is no restriction on the number of concurrently transmitted traffic flows. (6) If it is assumed that a maximum of N (N>R) elastic traffic flows are transported simultaneously over the link, then the M/G/R/N-PS model can be applied to calculate the average file transfer delay. The calculation of the mean sojourn time of the M/G/R/N-PS model is presented in Chapter 6.3.7.2. Given the maximum number of flows Nk for the service class k, the state probability equation is given in equation (7.4) which is based on the equation (6.28). (j<R) (7.4) With the given state probability, the average number of connections can be derived from By applying Little's law, the average transfer delay is obtained 7.3 Dimensioning for Elastic Traffic E M/G/R/N-PS according to equation (6.29). Here 2 denotes the average flow arrival rate of the service class k in Erlang and p(Nk) represents the probability of having above N connections in the network. It is noted that the above approach is for calculating the average application delay per AF or BE PHB. It can be also applied to a single AF class with different drop levels. Because each drop level belongs to one specific PHB, The above proposed extension on the M/G/R-PS model for the dimensioning of the IP- based lub with DiffServ QoS structure was published by the author in [LBG+08]. 7.3.2 Validation of Analytical Dimensioning Models This section validates the proposed analytical dimensioning approach for transport the elastic traffic on the AF or BE PHB, to guarantee certain application delay QoS of a service class by means of simulations. The simulation model is based on the simplified IP-based UTRAN model described in section 5.5.2. The simulation scenario consists of seven traffic types in UMTS. Table 7.1 describes the used service classes and their mapping to the DiffServ PHBs. In the investigated scenario, each Node B transmits 10 elastic traffic flows over AF11, 10 flows on AF21, 10 flows on AF31, 6 flows on AF41, 5 flows ove