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.
