ork reference model for the support of femto-cells, or alternatively Home eNB (HeNB) that includes a set of S1 interfaces to connect the HeNB to the EPC. The configuration and authentication entities as shown here are common between HeNBs and Home NBs (HNB). The HeNB GW serves as a focal point for the control-plane, particularly the S1-MME interface. The S1-U interface from the HeNB may be terminated at the HeNB GW, or a direct logical user-plane connection between HeNB and S-GW may be used. Release 9 of 3GPP specifications do not support X2 interface between HeNBs. The extended definition of S1 reference point includes the interface between the following entities: HeNB GW and the core network; HeNB and the HeNB GW; XiA femto-cell is a small cellular base station typically designed for use in residential or small office environments. It connects to the operator's network via a broadband connection. A femto-cell allows the operators to extend service coverage indoors, especially where network access would otherwise be limited or unavailable. The femto-cell incorporates reduced functionalities of a typical base station and allows a simpler and self-organized deployment. CHAPTER 2 WiMAX Network Architecture E-UTRAN FIGURE 2-12 Overall E-UTRAN architecture including HeNBs [31] HeNB and the core network; eNB and the core network. As shown in Figure 2-12, the HeNB GW appears to the MME as an eNB, and to the HeNB as an MME. The S1 interface between the HeNB and the EPC is the same regardless of whether the HeNB is connected to the EPC through a HeNB GW. The HeNB GW is connected to the EPC in a way that inward and/or outward movement toward the cells served by the HeNB GW does not necessarily require inter-MME handovers. The functions supported by the HeNB are similar to those supported by an eNB (with the exception of Non Access Stratum Node Selection Function [31]) and the protocols between a HeNB and the EPC are the same as those between an eNB and the EPC. The HeNB performs the same functions as an eNB, as described 