A control-plane interface is established between a cellular radio access node and an anchor for at least first and second non-cellular radio access nodes (such as API and AP2); and thereafter during mobility of a user equipment (UE) from API to AP2, the anchor relocates a user-plane interface for a radio link allocated to the UE from API to AP2 while maintaining the established control-plane interface for the radio link. When implemented for LTE-WLAN Aggregation (LWA), the control-plane interface is Xw-C with a corresponding control plane wireless termination (WT-C), the user-plane interface is Xw-U with a corresponding user plane wireless terminations (WT-U); the cellular radio access node is an eNB, the APs belong to the anchor and have BSSs that belong to a same mobility set that is configured for the UE by the eNB; the anchor is the WT-C, and the APs are WT-Us.