US Patent 9391824 Transmission timing in a carrier group

Transmission timing of a random access preamble in an uplink carrier of a carrier group being determined employing a synchronization signal transmitted on a downlink carrier of the carrier group. The wireless device receives a time alignment command from the base station. The time alignment command comprises a time adjustment value and an index identifying the carrier group. The wireless device applies the time adjustment value to uplink signals transmitted on all activated uplink carriers in the carrier group.