A wireless device receives a control message comprising configuration parameters of a plurality of cells grouped into a plurality of cell groups. The wireless device transmits a first sounding reference signal (SRS) in a first cell group overlapping in time with transmission of a first random access preamble in a second cell group. Transmission of a second SRS in the first cell group is dropped if: the second SRS transmission and a second random access preamble transmission in the second cell group overlap in time and the wireless device has insufficient transmission power.