ing for voice traffic with Erlang-B (ATM VS. IP) 12000 ATM lub (1% blocking) 10000 IP lub (1% blocking) ATM lub (5% blocking) IP lub (5% blocking) offered voice traffic load (kbps) Figure 7.7: ATM vs. IP (without multiplexing) link bandwidth over traffic load voice scenario: QoS target: 1% and 5% connection reject ratio It can be seen that the IP transport requires much higher bandwidth than the ATM, as the IP has a much lower bandwidth efficiency for 12.2 kbps AMR voice bearer as shown in Figure 7.6 when not using any multiplexing scheme. In order to reduce the transport costs of IP, it is suggested to apply multiplexing schemes to improve the bandwidth efficiency. First investigations of various multiplexing schemes are presented by the author in [LC*07] and the importance of optimization is addressed. The following several examples compare the lub dimensioning for web traffic to guarantee a target end-to-end delay factor of 1.25 for transferring a 50 kbyte web page. Figure 7.8 compares the dimensioning for RAB 128 kbps, and Figure 7.9 for RAB 64 kbps and RAB 384 kbps in the ATM and IP-based lub. IP lub ATM lub IP RAN without LIPE ATM RAN 200 400 600 800 1000 1200 1400 1600 1800 2000 Traffic load (kbps) (a) delay over load (link utilization) (b) capacity over traffic load Figure 7.8: ATM vs. IP: web scenario, RAB 128 kbps, no CAC, constant page size of 50 kbyte, target delay factor f =1.25 7.4 Comparing the ATM and IP-Based lub RAB 64kbps RAB 384kbps IP RAN without LIPE IP RAN without LIPE ATM RAN ATM RAN Traffic load (kbps) Traffic load (kbps) Figure 7.9: ATM vs. IP (capacity over traffic load): web scenario, RAB 64 kbps (left) and RAB 384 kbps (right), no CAC, page size =50 kbyte, target delay factor f = 1.25 The left graph in Figure 7.8 shows the average transfer delay with RAB 128 kbps over different loads (link utilizations). The results in the graph are taken from simulations with the ATM and IP based UTRAN simulation model. It is seen in Figure 7.8 that when the load is low, the obtained average applicat