The present disclosure provides several methods, user equipment (UEs) and base stations for transmitting uplink signals. After receiving uplink synchronization command information, the UE may transmit an uplink signal on at least one idle unlicensed cell. Besides, the UE may try to transmit the uplink signal on multiple uplink signal resources within an uplink signal transmission window. By using the present disclosure, transmission probability of uplink signals may be improved, and time delay of uplink synchronization may be shortened.