S net- work. Table 17.4 shows the corresponding end-to-end handoff delay including the queuing delay at different servers and the transmission delay over the Internet. Figure 17.12 shows the handoff delay component due to wireless access with the increase of SIP-based session request rate. The request rate of the SIP-based session in an MH is assumed to be = 50 requests/s when the channel FER is varied. On the other hand, the channel FER is kept constant at 0.05 when the arrival rate (XM) for a SIP-based session is varied. C 2009 by Taylor & Francis Group, LLC SIP-Based Mobility Management and Its Performance Evaluation 9.6 Kbps channel 19.2 Kbps channel 128 Kbps channel Frame error rate FIGURE 17.11 Wireless delay VS. FER for MH moving to UMTS network from another UMTS network or a WLAN. The corresponding variation of handoff delay with the channel FER and SIP session request rate, for the case when the MH moves to WLAN, are given in Figure 17.13 and Figure 17.14. Table 17.5 shows the end-to-end handoff delay for an MH moving to a WLAN access network. Observe that the component of handoff delay due to wireless access for a 128 Kbps GPRS radio access of a UMTS network is 1.404818 S, where the channel FER is 0.05 and the SIP-based multimedia session arrival rate is 50/s. Whereas for the 11 Mbps WLAN, the handoff delay is only 0.267 ms. As mentioned earlier, to ensure QoS for streaming multimedia, the maximum handoff delay should be ideally less than 100 ms and not more than 200 ms. Moreover, such abrupt variation in end-to-end delay due to handoff essen- tially means unacceptable delay jitter for multimedia streaming applications. Clearly, this requirement cannot be satisfied for a UMTS network even with a channel data rate of 128 Kbps. Figure 17.15 shows the exponential decrement of the total handoff delay with the increase of access bandwidth available for handoff. With higher speed data access (on the order of Mbps) as promised in the emerging 4G networks [32], the handoff delay will be within the stip- ulated 