nced Urban Microcell Urban Urban Microcell Urban Macrocell Test Macrocell Test Environment Environment Environment Environment (3 km/h) (30 km/h) (3 km/h) (30 km/h) Legacy Mobile WiMAX based on Release 1.0 IEEE 802.16m Introduction xxiii evolved UMTS terrestrial radio access network substantially improved end-user throughputs, and sector capacity, and reduced user-plane and control-plane latencies, bringing a significantly improved user experience with full mobility. With the emergence of the Internet protocol as the protocol of choice for carrying all types of traffic, the 3GPP LTE provides support for IP-based traffic with end-to- end quality of service. Voice traffic is supported mainly as voice over IP, enabling integration with other multimedia services. Unlike its predecessors, which were developed within the framework of UMTS architecture, 3GPP specified an evolved packet core architecture to support the E-UTRAN through a reduction in the number of network elements and simplification of functionality, but most importantly allowing for connections and handover to other fixed and wireless access technologies, providing network operators with the ability to deliver seamless mobility experience. Similar to the IEEE 802.16, 3GPP set aggressive performance requirements for LTE that relied on improved physical layer technologies, such as OFDM and single-user and/or multi-user MIMO techniques, and streamlined Layer 2/Layer 3 protocols and functionalities. The main objectives of 3GPP LTE were to minimize the system and user equipment complexities, to allow flexible spectrum deployment in the existing or new frequency bands, and to enable coexistence with other 3GPP radio access technologies. The 3GPP LTE has been used as the baseline and further enhanced under 3GPP Release 10 to meet the requirements of the IMT-Advanced. A candidate proposal based on the latter enhancements (3GPP LTE-Advanced) was submitted to the ITU-R and subsequently qualified as an IMT-Advanced tech- nology. However, concurrent with the 3GPP LT