Access Service Network Gateway (ASN-GW)

The base stations within an ASN-GW group (i.e., all base stations connected to the same ASN-GW) are connected through R8 reference point. Furthermore, the base stations within an ASN-GW group are separately connected to the ASN-GW via R6 reference point, as shown. 

The base station is a logical entity that implements a full instance of Medium Access Control (MAC) and Physical Layer (PHY) protocols, as specified by the IEEE 802.16-2009 standard and includes one or more access functions. A BS instance represents one sector with one frequency assignment. It incorporates scheduler functions for uplink and downlink radio resources, which are typically vendor specific.

The ASN-GW is a logical entity that represents an aggregation of control functions that are either paired with a corresponding function in the ASN (e.g., BS instance), a resident function in the CSN, or a aggregation of control functions that are either paired with a corresponding function in the ASN (e.g., BS instance), a resident function in the CSN, or a function in another ASN. The ASN-GW may also perform bearer-plane routing or bridging functions. A BS is associated with a default ASN-GW; however, the ASN-GW functions may be distributed among multiple ASN-GWs located in one or more ASNs. 

The ASN functions in an ASN-GW can be divided into two groups, i.e., the Decision Point (DP) and the Enforcement Point (EP) functions. The EP category includes bearer-plane functions and the DP category includes non-bearer-plane functions. If such functional split is implemented in ASN-GW, the EP and DP functional groups would include bearer-plane and non-bearer-plane functions, respectively, and are interfaced using R7 reference point.