Manual

Compression. All of these functions are carried by the physical layer over the air as shown in the following
figure:
Figure 8: e-UTRAN Uu Interface Logical Representation
The physical layer in LTE is based upon the Orthogonal Frequency Division Multiplexing (OFDM)
using Orthogonal Frequency Division Multiple Access (OFDMA) in the downlink and variant of this
Single Carrier Frequency Division Multiple Access (SC-FDMA) in the uplink.
•
S1 Interface: The communication between the E-UTRAN and the EPC has been designated to the S1
interface. The S1 interface has been separated by the Control plane signalling and User plane traffic:
◦
S1-MME: The S1 variant used for Control plane signalling is referred to as S1-MME interface.
◦
S1-U: The S1 variant used for User plane traffic is referred to as S1-U interface.
The S1-MME interface is governed by the S1-AP protocol, whose functions include:
•
E-RAB Management Function: This functionality is responsible for setting up, modifying and
releasing evolved Radio Access Bearers (E-RABs), which are triggered by the MME. The release
of E-RABs may be triggered by the eNodeB as well.
•
Initial Context Transfer Function: This functionality is used to establish an S1-UE context in
the eNodeB. It is also used to setup the default IP connectivity, to setup one or more E-RAB(s) if
requested by the MME, and to transfer NAS signalling related information to the eNodeB if needed.
•
UE Capability Information Indication Function: This functionality is used to provide the UE
Capability Information when received from the UE to the MME.
•
Paging: This functionality provides the EPC with the capability to page the UE.
•
S1 Interface Management Functions: These functions comprise the following:
◦
Reset functionality for ensuring a well defined initialization on the S1 interface.
HeNB-GW Administration Guide, StarOS Release 19
12
HeNB Gateway in Wireless LTE Network
Supported Logical Interfaces