 Often referred as hard-blocking. Deploying 3G Networks Erlang Figure 7.10 Nominal RNC traffic loads in Mbps VS. Erlang (000s). The lub, Iu, and Iur interfaces will in general support sufficient capacity margins, and the overheads will not exceed peak rates. Thus, the key RNC dimensioning parameters include the number of Node Bs in the coverage area, and the average traffic in this given area. The first parameter gives the: RNC No_node_B = Total no. node Bs/no. Node Bs supported per RNC, and the second one allows us to calculate throughput capacity, i.e. RNC throughput max1[CSavg/X1 PSavg/Y17). We can obtain the initial value of NCthroughput from the CS and PS average traffic uniformly distributed in the target area. We can modify the PS (Mbps) VS. CS (Erlang) output of Figure 7.10 to a PS VS. CS (Mbps) output by translating the CS traffic from Erlang to Mbps (i.e. Erlang X 12.2 kbps AMR voice codec). Then we can illustrate the RNC throughput in terms of average value of the CS and PS traffic in Mbps as shown in Figure 7.11. However, the average traffic will not take into account the traffic burstiness. Thus, peak values should be pro- jected iteratively using the Gaussian Law. In general, the peak values will mean that the proportion of PS traffic will increase. PS throughput [Mbps] CS PS avg CS throughput [Mbps] Figure 7.11 Estimation of the RNC throughput. The UMTS Network and Radio Access Technology RADIO NETWORK DIMENSIONING FIELD STUDY The analysis assumptions for the projected subscriber growth and traffic flow illustrated in Table 7.5 take the values shown in Table 7.8. These assumptions provide the generic set of information to calculate the number of radio network elements required for the coverage mentioned in Section 7.5. Notice for example that we set the blocking characteristics to 1%; however, it is often set to 2%. The design assumes UL limitation by setting the load to 50%. With opti- mized interference techniques, UL load can reach up to 65%. Antenna heights for the MS can vary from 1.5 to 1.7 m