, hence also called as Provider Edges (PEs), which are responsible for providing a tunnel emulating ATM services over the Ethernet network for the corresponding CEs. Between these two routers, an Ethernet Pseudo-Wire is established through the Ethernet network (which is a Packet Switched Network). Thus, the ATM cells coming from the Node B or RNC will be encapsulated into Ethernet packets within the PWE routers and then carried over the emulated Ethernet circuit, i.e. the Ethernet Pseudo-Wire. After the Ethernet packets arrive at the egress of the Ethernet network, they are decapsulated 2 UMTS Evolution to the ATM cells and forwarded to their destination. Usually Ethernet switches can be used within the Carrier Ethernet transport network as an intermediate switches to multiplex/de- multiplex outgoing/incoming Ethernet frames. ATM Link Ethernet ATM Link Ethernet Ethernet Network Node B Router Router ..... N ..... 32 1 Ethernet Packet Ethernet Packet Ethernet Packet ATM cells ATM cells Ethernet Pseudo-Wire Figure 2.3: Carrier Ethernet-based UTRAN using PWE3 The Pseudo-Wire solution is becoming a popular approach for mobile wireless operators for the mobile network migration phase, because Pseudo-Wire is the enabling technology for transporting both mobile voice and data traffic over new high-capacity, lower-cost packet networks in the RAN. It gives operators the possibility to choose among multiple packet network technologies in the RAN, including Carrier Ethernet, MPLS, xDSL and even broadband packet radio (WiMAX). The Pseudo-Wire solution also provides support for all generations of mobile wireless services and ensures a smooth transition from one generation to the next. A detailed investigation on the performances of a PWE-based UTRAN by the author was published in [LZK*08]. 2.3.5 LTE and SAE The roadmap of Next Generation Mobile Network (NGMN) is to provide mobile broadband services. Services like high-speed internet access, distribution of video content (Mobile TV), fast interactive gaming, wireless DSL, fixed