Home eNodeB

A Home eNodeB, or HeNB, is the 3GPP's term for an LTE femtocell or Small Cell.

An eNodeB is an element of an LTE Radio Access Network, or E-UTRAN. A HeNB performs the same function of an eNodeB, but is optimized for deployment for smaller coverage than macro eNodeB, such as indoor premises and public hotspots.

Home Node B is 3G (UMTS) counterpart of the HeNB.

Architecture

Within an HeNB Access Network there are three new network elements: the Home eNodeB, the Security Gateway (SeGW) and the Home eNodeB Gateway, or HeNB-GW.

Home eNodeB (HeNB) – A HeNB provides LTE radio coverage for LTE handsets. HeNBs incorporate the capabilities of a standard eNodeB.

Security Gateway (SeGW) - Installed in an operator’s network, the Security Gateway establishes IPsec tunnels with HeNBs using IKEv2 signaling for IPsec tunnel management. IPsec tunnels are responsible for delivering all voice, messaging and packet data services between HeNB and the core network. The SeGW forwards traffic to HeNB-GW.

HeNB Gateway (HeNB-GW) - It is an optional network element (NE) installed within an operator’s network. If it is present, it is placed between the HeNB and the MME and it aggregates traffic from a large number of HeNBs back into an existing core service network through the standard S1 interface.

Architectural Variations

There are three architectural variations as described in 3GPP TR23.830. The variations are driven by the following factors: 1) whether the HeNB-GW is present or not, and 2) if HeNB-GW is present, whether the S1 User Plane (S1-U) goes through it or not.

Variation 1

HeNB-GW is present and it aggregates both S1-MME and S1-U.

Variation 2

HeNB-GW is not present; in this case, the HeNB is directly connected with MME and SGW (i.e. same architecture with normal macro eNodeB).

Variation 3

HeNB-GW is present and it aggregates S1-MME only; S1-U interface is directly connected with SGW

Logical Interface

The logical interface on HeNB is the same with the macro eNodeB architecture. There are, however, differences in terms of the termination point of the logical interface depending on whether HeNB-GW is present or not.

Control Plane (CP) Interface - The interface between the HeNB and the HeNB-GW, and between HeNB-GW and MME is S1-MME. From protocol perspective, the same S1AP and X2AP protocols are used in HeNBs as well as macro eNodeBs.

User Plane (UP) Interface - The interface between HeNB and the HeNB-GW, and between HeNB-GW and S-GW is S1-U. If the HeNB-GW is present, then the UP can be carried through either the HeNB-GW or directly to the S-GW; both topologies are possible.

O&M Interface - Management interface between HeNB and Home eNodeB Management System (HeMS). It uses TR-069 (CWMP) as the management protocol and TR-196 data model. The main purpose is for the configuration of the HNB.

Standard

The following 3GPP documents are specifically on HeNB: