LTE Network Architecture
Different from a traditional 3GPP network, an LTE network uses the single-layer architecture that combines radio network controller (RNC) nodes and NodeB nodes into E-UTRAN NodeB (eNodeB) nodes, as shown in Figure 12-1. The eNodeB nodes complete circuit switching on the base stations. This single-layer architecture simplifies the network, shortens the system delay, and reduces the costs in network construction and maintenance.
Table 12-1 describes LTE network elements (NEs). A router connects to the LTE network as user equipment (UE).
NE |
Description |
|---|---|
PDN gateway |
Packet data network (PDN) gateway. The PDN gateway connects UEs to an external PDN. The data of UEs and the external PDN needs to pass through the PGW. |
Serving gateway |
Serving gateway (SGW). The SGW routes and forwards data packets and manages user mobility as well as mobility between LTE and other 3GPP technologies. |
SGSN |
Serving GPRS support node (SGSN). The SGSN is an important part of the packet switched domain on the General Packet Radio Service (GPRS), Time Division-Synchronous Code Division Multiple Access (TD-SCDMA), and Wideband Code Division Multiple Access (WCDMA) networks. The SGSN routes and forwards packets, manages mobility, sessions, and logical links, performs authentication and encryption, and generates and exports call detail records (CDRs). |
eNodeB |
eNodeB connects to the SGW using an S1-UP interface and communicates with a UE using a Uu interface, completing protocol processing on the S1-UP interface and Uu interface physical layer. |
UE |
User equipment (UE). On 3G and 4G networks, UEs include mobile phones, smart terminals, multimedia devices, and streaming devices. |