CSN-anchored Mobility

The CSN-anchored mobility refers to mobility across different ASNs alternatively to mobility across different IP subnets, and thereby requires network layer mobility management. The mobile IP protocols are used to manage mobility across IP subnets, and to enable CSN-anchored mobility. This section describes mobile IP based macro-mobility between the ASN and CSN across R3 reference point. In the case of IPv4, this implies re-anchoring of the current FA to a new FA, and the consequent binding updates (or MIP re-registration) to update the upstream and downstream data forwarding paths. In CSN-anchored mobility, the anchor mobile IP FA of the MS is changed. The new FA and CSN exchange messages to establish a data forwarding path. The CSN-anchored mobility management is established between ASN and CSN that are in the same or different administrative domains. The mobility management may further extend to handovers across ASNs in the same administrative domain. The procedures for CSN-anchored mobility management and the change of MS point of attachment to the ASN may not be synchronized. In this case, the procedures may be delayed relative to the completion of link layer handover by the MS. 

In an intra-NAP R3 mobility scenario, an MS is moving between FAs within a single NAP domain. The R3 mobility event results in a handover between two FAs, thereby relocating the ASN R3 reference anchor point in the NAP. Note that R3 mobility does not automatically terminate or otherwise interfere with idle/sleep operation of the MS. The CSN-anchored mobility accommodates the scenario in which the MS remains in idle state or sleep mode until it is ready to transmit uplink traffic or is notified of downlink traffic by the serving BS. In all non-roaming scenarios, the HA is located in the CSN of H-NSP. For roaming scenarios, the HA is located in the CSN of either the H-NSP or V-NSP, depending on roaming agreement between H-NSP and V-NSP, user subscription profile and policy in H-NSP. The CSN-anchored mobility within a single NAP administrative domain does not introduce significant latency and packet loss. A make-before-break handover operation (i.e., when a data path is established between the MS and target BS before the data path with the serving BS is broken) is feasible within the same NAP administrative domain. To accomplish this procedure, the previous anchor FA maintains data flow continuity while signaling to establish the data path to a new anchor FA. The PMIP procedures do not require additional signaling over-the-air or additional data headers to perform CSN-anchored mobility. The CSN-anchored mobility activities are transparent to the MS. The MS uses Dynamic Host Configuration Protocol (DHCP) for IP address assignment and host configuration. DHCP is a network application protocol used by devices to obtain configuration information for operation in an IP network. This protocol reduces system administration workload, allowing devices to be added to the network with minimal user intervention