LTE, LTE-Advanced and WiMAX: Towards IMT-Advanced Networks

Overview of LTE Networks

LTE is the Radio Access Network (RAN) of the Evolved Packet System (EPS). The network core component of EPS, called Evolved Packet Core (EPC) or System Architecture Evolution (SAE), is designed to be a completely IP-centric network that provides QoS support and ensures revenue and security. Figure 9.1 shows the basic architecture components of LTE, which consists of enhanced nodeBs (eNBs) at the RAN, and Mobility Management Entities (MMEs) and Serving Gateways (S-GW) at the core. The eNBs interconnect through an interface called the X2 interface, while they are connected to entities at the core (MMEs and S-GWs) using the S1 interface [1].

Figure 9.1 Basic LTE and LTE-Advanced Architecture. Reproduced by permission of © 2010 3GPP. Further use is strictly prohibited.

The LTE architecture depends on a network configuration that is simpler that its predecessor, the UMTS Terrestrial Access Network (UTRAN). In LTE, which is also called evolved UTRAN (EUTRAN), RAN considerations and decisions are all handled by the eNB, while relevant considerations for the core network are processed at the core. This “functional split”, elaborated upon in Figure 9.2, directly results in substantial performance enhancements in cellular networks. The split further identifies the boundaries between the two network management and control stratums, where the Access Stratum (AS) is ...