A wireless communication user terminal obtains uplink access configuration information on a physical downlink control channel (PDCCH) addressed to a plurality of user terminals by processing the PDCCH based on a first system information received from a base station on a physical broadcast channel (PBCH) and based on synchronization information. The terminal sends a signature waveform based on the uplink access configuration information, prior to receiving system information in addition to the first system information, whereby the signature waveform enables the base station to transition from a relatively low power operating mode to a relatively high power operating mode.