4.0 General

36.3003GPPEvolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN)Overall descriptionRelease 17Stage 2TS

The E-UTRAN consists of eNBs, providing the E-UTRA user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UE. The eNBs are interconnected with each other by means of the X2 interface. The eNBs are also connected by means of the S1 interface to the EPC (Evolved Packet Core), more specifically to the MME (Mobility Management Entity) by means of the S1-MME interface and to the Serving Gateway (S-GW) by means of the S1-U interface. The S1 interface supports a many-to-many relation between MMEs / Serving Gateways and eNBs.

The E-UTRAN architecture is illustrated in Figure 4 below.

Figure 4-1: Overall Architecture

If the eNB supports SIPTO@LN with collocated L-GW, it shall support an S5 interface towards the S-GW and an SGi interface towards the IP network. See clause 4.8.2 for the details of the architecture and functions in case SIPTO@LN with collocated L-GW is supported.

The E-UTRAN may also comprise LMUs (Location Measurement Unit) (see TS 36.305 [51]) used for Uplink positioning.

For NB-IoT the positioning is supported based on the existing LCS architecture.