t of the access network; Flexible billing; Access type selection optimizing service delivery. Manufacturer or Application Developer Reduced cost of terminals and network equipment based on global economies of scale; Access to global markets; Open physical and logical interfaces between modular and integrated subsystems; Programmable/configurable platforms that enable fast and low-cost development. The capabilities of IMT-2000 systems have continuously evolved over the past decade as IMT-2000 technologies have been upgraded and widely deployed. From the radio access perspective, the evolved IMT-2000 systems have built on the legacy systems, further enhanced the radio interface functionalities/protocols, and at the same time new systems have emerged to replace the existing IMT-2000 radio access systems in the long-term. This evolution has improved the reliability and throughput of the cellular systems and promoted the development of an expanding number of services and applications. The similarity of services and applications across different IMT tech- nologies and frequency bands is not only beneficial to users, but also a similar user experience generally leads to a large-scale deployment of products and services. The technologies, applications, and services associated with systems beyond IMT-Advanced could well be radically different from the present systems, challenging our perceptions of what may be considered viable by today's standards and going beyond what has just been achieved by the IMT-Advanced radio systems. The IEEE 802.16 Working Group began the development of a new amendment to the IEEE 802.16 baseline standard in January 2007 as an advanced air interface, in order to materialize the ITU-R vision for the IMT-Advanced systems as laid out in Recommendation ITU-R 11645. The requirements for the IEEE 802.16m standard were selected to ensure competitiveness with the emerging 4th generation radio access technologies, while extending and significantly improving the functionality and efficiency of the legacy