Apparatus and methods for unknown physical uplink control channel (PUCCH) secondary cell (SCell) activation are proposed. The network node may transmit a PUCCH SCell activation command for an unknown target PUCCH SCell to the UE. After receiving the PUCCH SCell activation command for the unknown target PUCCH SCell, the UE may transmit a layer 1 (L1) report or a layer 3 (L3) report for the unknown target PUCCH SCell to the network node before the unknown target PUCCH SCell is activated. The network node may obtain measurement information based on the L1 report or the L3 report before the unknown target PUCCH SCell is activated. Then, the network node may perform corresponding operations based on the L1 report or the L3 report before the unknown target PUCCH SCell is activated.