A method for use in a Wireless Transmit/Receive Unit (WTRU). The method comprises: receiving, using an active receiver, system information comprising a first system information set, wherein the first system information set is currently valid for the WTRU; storing the system information; deactivating the active receiver and activating a passive receiver; determining whether a difference between a first parameter in the BSSI and a first parameter in the first system information set is greater than a threshold value, wherein on a condition that the difference is greater than the threshold value, reactivating the active receiver to receive a second system information set as a currently valid system information set for the WTRU.