-74746-9 Next Generation Mobile Communications Ecosystem Radio Access Backhaul Metro Network Backbone City A Microwave, Copper, ATM, Ethernet, SDH/SONET RING Common Core Network City B IP/MPLS Microwave, Copper, ATM, Ethernet, SDH/SONET RING IP-Transit City C Internet Microwave, Copper, ATM, Ethernet, SDH/SONET RING Figure 7.1 Transport network hierarchy the total network cost. Innovative transport solutions will be required to make it technically robust and economically cost effective. 7.2.1 Drivers The key drivers that necessitate making enhancements (CAPEX intensive) in the transport networks are: The most talked about driver for having a robust mobile backhaul solution is the growth of packet traffic. As mobile broadband technologies such as EPS, EV-DO Rev. B, HSPA+, and WiMAX start to penetrate the market, the usage of new services such as video calling, movies on the go, mobile TV, and SO on, will rise. This will increase the amount of traffic both originating and terminating in the RAN and may create bottlenecks in rest of the transport network. Another driver that has to be considered is the impact of Smart Antennas and MIMO (Multiple Input Multiple Output) technologies on the backhaul. The technologies will increase the capacity many folds at the cell sites and will necessitate the use of high capacity solutions. The third but less talked about driver has to do with the transition of 2G to 3G; the need to support multiple traffic types at the cell sites. This necessitates the use of hybrid solutions that can carry TDM, ATM, and IP traffic. The transition from TDM and ATM to IP will also require high quality aggregation platforms that can aggregate and transport 2G TDM traffic, 3G ATM traffic and 3G IP traffic with proper SLAs (Service Level Agreements). Transmission Networks 7.2.2 Challenges There is no standard that specifies how a transport network should be defined and implemented to optimally carry the traffic. Yet mobile backhaul networks constitute a significant component of the overall operational