1. A method comprising:receiving, by a wireless device, at least one control message comprising:
configuration parameters of a plurality of cells grouped into a plurality of timing advance groups (TAGs) comprising:
a first TAG comprising a first subset of the plurality of cells, first uplink transmission timing in the first TAG derived employing a first cell in the first TAG; and
a second TAG comprising a first unlicensed cell and a second unlicensed cell, second uplink transmission timing of the first unlicensed cell in the second TAG derived from:
a first signal received on the first unlicensed cell; and
a second signal received on the second unlicensed cell;
receiving a timing advance command (TAC) comprising a time adjustment value and a TAG index; and
applying, based on the TAG index, the TAC to the first uplink transmission timing of the first TAG or the second uplink transmission timing of the second TAG.