y, UMB an evolution to EV-DO and a potential competitor to 3G-LTE and WiMAX has been discontinued. This failure has demanded the EV-DO industry to find a new evolution path and this has turned out to be 3GPP 3G-LTE for the most players. The evolution of EV-DO is discussed in detail in the chapter. 1.2.5 Chapter 6 IEEE 802.20 Mobile-Fi Chapter 6 looks into IEEE 802.20 MobileFi technology, which is also known as MBWA (Mobile Broadband Wireless Access). It was initially proposed to counter WiMAX. Though the standard was completed in 2007, it has SO far failed to develop into any meaningful industry support until the writing of this book. The chapter goes on to describe MBWA air interface, architecture and performance. 1.2.6 Chapter 7 Transmission Networks The key aspects of transmission or transport systems are described in Chapter 7. The transmission networks can be divided into three segments, namely access (backhaul) network, metro or regional network and core (backbone) network. This segmentation is not standard and could vary from operator to operator and country to country. The key bottleneck of today's broadband networks is mobile backhaul. A number of technological alternatives are provided to address this challenge. In addition, some backhaul planning guidelines are presented in the chapter as well. Several technologies that can be used in metro and backbone segments are also presented. 1.2.7 Chapter 8 Core Networks and OSS Chapter 8 discusses two elements of the mobile networks, namely core networks and operational support systems. The evolution of 3GPP core networks with respect to different releases (Rel.99 to Rel.8) has been discussed in detail. We also briefly touched upon the core networks of EV-DO, WiMAX and MBWA. The role of various Standard Development Organizations (SDOs) and industry forums on OSS is discussed. Details of TMN (Telecommunications Management Network) and Next Generation OSS (NGOSS) are also provided in the chapter. Lastly, management reference models of both EPS and WiMAX are descr