Implementations described herein relate generally to a user device, to an access node, and to methods for a user device and for an access node. The user device includes a receiver configured to receive at least one downlink signal from an access node. The user device further includes a processor configured to measure the at least one downlink signal at two time instants, to determine if a difference of the measured at least one downlink signal at the two time instants exceeds a threshold, and to generate, when the difference exceeds the threshold, at least one uplink transmission. The user device further includes a transmitter configured to transmit the at least one uplink transmission over an uplink random access channel.