A sounding reference signal (SRS) is being scheduled for transmission in the last symbol of subframe n on a first cell in a first cell group. The last symbol overlaps in time with transmission of an uplink packet in subframe n+1 in a second cell in a second cell group. The wireless device transmits the SRS if a power parameter is less than or equal to a maximum allowable transmission power in the symbol. A calculation of the power parameter considers transmission power of the uplink packet if the overlap in time exceeds a first duration.