2010 propose RITs (3): WP 5D decides framework and key October 2010 (1): ITU proposed cut off for October 2009 characteristics of IMT-Advanced submission of candidate RIT RITs and SRITs February 2011 and SRIT proposals (4): WP 5D completes development of radio interface specification IMT-Advanced A2-01 Recommendations Figure 13.1 Schedule for the development of IMT-Advanced radio interface recommendations. Reproduced with permission from © 2008 ITU-R [2] The specifications are expected to be available at the end of 2010 and are expected to be frozen by March 2011. The IEEE 802.16 working group is developing the OFMDA based 802. 16m standard which is expected to meet the IMT-Advanced requirements. IEEE has proposed a single RIT (inclusive of TDD and FDD) to meet or exceed all IMT-Advanced requirements in all test environments. The IEEE 802.16m specifications are expected to be completed in 2010. Mobile Network Infrastructure Sharing The current mobile network operator business model is based on the operator's full ownership of the physical network assets. In the current form, the operator plans the network architecture and topology, acquires (buys or leases) and builds (civil works) sites, oversees the network implementation by suppliers and subcontractors, operates and maintains the network, creates, markets and provides services to its end users, and manages the customer relationship [7]. However, market saturation, rapid migration to 3G and 4G technologies, regulatory requirements, and competitive environments are all pushing the envelope. These conditions are pointing to a new element called Network Infrastructure Sharing which primarily involves active and passive sharing of infrastructure in the radio access and transmission networks among multiple operators. Passive sharing involves components such as the tower mast or pylons, cables, physical site or rooftop, shelter cabinets, power supply, air-conditioning, alarm systems, and SO on. Active sharing includes antennas, antenna systems, backhaul transmission 