A method of L1/L2-based mobility with signaling optimization using base (reference) configuration and replaceable (delta) configuration for candidate cells is proposed. All candidates can be configured at different levels provided by Radio Resource Control (RRC) signaling. To support L1/L2-triggered mobility (LTM), there is a common base configuration for candidates, and the candidates are modelled as replaceable configurations which are delta configurations on top of the common base configuration (instead of UE's current RRC configuration). The common and replaceable configurations are also referred to as reference configuration and candidate delta configuration. The candidate delta configuration is applied on top of the reference configuration to form a complete candidate configuration for handover.