WIMAX Mobility Management

The WiMAX network architecture supports two types of mobility: ASN-anchored mobility (intra-ASN) and CSN-anchored mobility. ASN-anchored mobility refers to a scenario where a mobile terminal moves between two base stations belonging to the same ASN while maintaining the same foreign agent at the ASN. The handover in this case utilizes R6 and R8 reference points. The CSN-anchored mobility refers to an inter-ASN mobility scenario where the mobile station moves to a new anchor foreign agent and the new FA and CSN exchange signaling messages to establish data forwarding paths. The handover in this case is performed via R3 reference point with tunneling over R4 to transfer undelivered packets. 

Figure below illustrates three different mobility scenarios supported in WiMAX networks. When the mobile station moves from positions 1 to 2, or 1 to 3, an ASN-anchored mobility through R8 or R6 reference points, respectively, is implied, whereas moving from position 1 to 4 involves a CSN-anchored mobility scheme though R3 reference point.