LTE - Major Network Elements and Functions

LTE - Major Network Elements and Functions (E-UTRAN: eNB, HeNB, HeNB-GW, and EPC/aGW: MME, S-GW, P-GW)

(eNB) E-UTRAN eNB Function
- Selection of aGW at attachment;
- Routing towards aGW at RRC activation;
- Scheduling and transmission of paging messages (originated from the MME);
- Scheduling and transmission of broadcast information (originated from the MME or O&M) - BCCH information;
- Scheduling and transmission of ETWS messages (originated from the MME).
- Measurement and measurement reporting configuration for mobility and scheduling;
- Selection of an MME at UE attachment when no routing to an MME can be determined from the information provided by the UE;
- Dynamic allocation of resources to UEs in both uplink and downlink;
- The configuration and provision of eNB measurements;
- Functions for Radio Resource Management: Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both uplink and downlink (scheduling);
- IP header compression and encryption of user data stream;
- Routing of User Plane data towards Serving Gateway;
- Radio Bearer Control;
- Radio Admission Control;
- Mobility Control in LTE_ACTIVE state.

(HeNB) E-UTRAN HeNB Function
- The functions supported by the HeNB shall be the same as those supported by an eNB (with the possible exception of NNSF) and the procedures run between a HeNB and the EPC shall be the same as those between an eNB and the EPC.
- The HeNB hosts the same functions as an eNB as described but with the following additional specifications in case of connection to the HeNB GW:
- Discovery of a suitable Serving HeNB GW
- A HeNB shall only connect to a single HeNB GW at one time, namely no S1 Flex function shall be used at the HeNB in case of connection to the HeNB GW.
- If the HeNB is connected to a HeNB GW, it will not simultaneously connect to another HeNB GW, or another MME.
- The TAC and PLMN ID used by the HeNB shall also be supported by the HeNB GW.
- When the HeNB connects to a HeNB GW, selection of an MME at UE attachment is hosted by the HeNB GW instead of the HeNB;
- HeNBs may be deployed without network planning. A HeNB may be moved from one geographical area to another and therefore it may need to connect to different HeNB GWs depending on its location.

(HeNB GW) E-UTRAN HeNB GW Function
- Relaying UE-associated S1 application part messages between the MME serving the UE and the HeNB serving the UE;
- Terminating non-UE associated S1 application part procedures towards the HeNB and towards the MME. Note that when a HeNB GW is deployed, non-UE associated procedures shall be run between HeNBs and the HeNB GW and between the HeNB GW and the MME.
- Supporting TAC and PLMN ID used by the HeNB.
- X2 interfaces shall not be established between the HeNB GW and other nodes.
- Optionally terminating S1-U interface with the HeNB and with the S-GW.
- Optionally performing paging optimisation in case the Allowed CSG List of the paged UE is included in the PAGING message.

(HeNB) Interface for HeNB and HeNB GW

§- The E-UTRAN architecture may deploy a Home eNB Gateway (HeNB GW) to allow the S1 interface between the HeNB and the EPC to scale to support a large number of HeNBs.

- The S1 interface is defined as the interface:

Ÿ

• Between the HeNB GW and the Core Network (EPC),
• Between the HeNB and the HeNB GW,
• Between the HeNB and the Core Network,
• Between the eNB and the Core Network.

§- The HeNB GW serves as a concentrator for the C-Plane (S1-C), specifically the S1-MMEinterface.

§- The S1-U interface from the HeNB may be terminated at the HeNB GW, or a direct logical U-Plane connection between HeNB and S-GW may be used

§

(MME) EPC MME Function
- NAS signalling;
- NAS signalling security;
- AS Security control;
- Inter CN node signalling for mobility between 3GPP access networks;
- Idle mode UE Reachability (including control and execution of paging retransmission);
- Tracking Area list management (for UE in idle and active mode);
- PDN GW and Serving GW selection;
- MME selection for handovers with MME change;
- SGSN selection for handovers to 2G or 3G 3GPP access networks;
- Bearer management functions including dedicated bearer establishment;
- Roaming;
- Authentication;
- Support for ETWS message transmission.

(S-GW) EPC S-GW Function
- The local Mobility Anchor point for inter-eNB handover;
- Mobility anchoring for inter-3GPP mobility;
- E-UTRAN idle mode downlink packet buffering and initiation of network triggered service request procedure;
- Lawful Interception;
- Packet routeing and forwarding;
- Transport level packet marking in the uplink and the downlink;
- Accounting on user and QCI granularity for inter-operator charging;
- UL and DL charging per UE, PDN, and QCI

(P-GW) EPC P-GW Function
- Per-user based packet filtering (by e.g. deep packet inspection);
- Lawful Interception;
- UE IP address allocation;
- Transport level packet marking in the downlink;
- UL and DL service level charging, gating and rate enforcement;
- DL rate enforcement based on APN-AMBR;

Further Study and Document refers to https://docs.google.com/fileview?id=F.7fc06ed5-86d7-4432-9f8d-7cbde494eb98