In this tutorial, we will discuss on the LTE Network Interface.
LTE – S1 Interface:
S1 interface is between EUTRAN and EPC. On the EUTRAN side the access point is E-NodeB and the core side the access point is either the control plane MME or the user plane S-GW.
Two types of S1 interface are defined (S1-MME for control plane and S1-U for user plane) .
LTE S1- MME interface has some special characteristics. It is used to deliver signalling protocol between eNodeB and MME. It consists of SCTP which is known as Stream Control Transmission Protocol. This is also supports Multiple UEs with a single SCTP association. It also provides guaranteed data delivery.
The LTE S1-MME is responsible for EPS bearer setup and release procedures. Also it uses for handover signaling procedure, the paging procedure and the NAS transport procedure.
The S1-U will be setup using signaling over S1-MME.
LTE X2 Interface:
The X2 interface support of exchanging of both control plane and user plane data between two EnodeBs.
Also support forwarding of PDUs between tunnel endpoints.
X2-AP (X2 Application Protocol) resides on SCTP. This is one of the principles of Control Pannel
Function of X2 interface:
- The X2 interface controls the handover of the certain UE from one EnodeB to another.
Handover include the transfer of UE context. UE context is required information to maintain the service for the UE. - Also supports load managements and inter cell interference coordination. In load management information about current traffic load will be exchanged between EnodeBs.
- One EnodeB can also inform neighboring ENodeBs about its downlink power restriction per resource block as an input into the neighboring ENodes scheduling decisions.
Now we have understood the LTE Network Interface. Let’s discuss LTE Network Interface in next tutorial.