ons is all about uniting all forms of communication, including voice, email, fax, VoIP, conferencing, and desktop applications. Internet IP backbone Figure 11.22 WiMAX network Next Generation Mobile Communications Ecosystem 11.11 Summary Insights Chapter 11 primarily discussed end-to-end network architecture of next generation mobile technologies, interoperability between them and FMC. The interworking is becoming a very interesting topic with the emergence of EPS as the major mobile broadband technology and the death of UMB. The interworking between EPS, EV-DO, and WiMAX is a daunting challenge. There are many unresolved mysteries that need to be solved to fully materialize interoperability among the various radio access technologies. There are several issues that require further study, including, but not limited to security optimization to achieve fast handover, information sharing on neighboring heterogeneous radio access cells, achieving end-to-end QoS, introduction and optimization of IP backhaul, and SO on. There are many ongoing activities in 3GPP, 3GPP2 and WiMAX Forum to further refine the mechanisms for integration and interworking of EV-DO and WiMAX with EPS. FMC seems to have a long way to go in order to be fully materialized. Although Common IMS initiative is a key step in this direction, the operators still cannot see ROI happening in the foreseeable future, especially with the challenges it brings. References 1. Asif, S.Z. (2007) Wireless Communications Evolution to 3G and Beyond, Artech House, Inc., Norwood, MA. 2. Taaghol, P., Salkintzis, K., and Iyer, J. (2008) Seamless integration of mobile WiMAX in 3GPP networks. IEEE Communications Magazine, 46 (10), 74-85. 3. WiMAX Forum (2006) Mobile WiMAX - Part I: A Technical Overview and Performance Evaluation, WiMAX Forum. 4. WMF - T32-002-R010v04 (2009) WiMAX Forum Network Architecture Stage 2 Part 1, WiMAX Forum, February. 5. 3GPP TS 23.060 (V 7.2.0) (2006) General Packet Radio Service (GPRS); Service description; Stage 2. Technical Specification (Rel