Patent ID: 8625404

Claim:
A method comprising: a) receiving, by a wireless device, at least one radio resource control (RRC) message from a base station, said at least one RRC message causing in said wireless device: i) configuration of a plurality of carriers comprising a first carrier and at least one second carrier; ii) assignment of a second carrier to a second carrier group in a plurality of carrier groups, said plurality of carrier groups comprising: (1) a first carrier group comprising a first subset of said plurality of carriers, said first subset comprising said first carrier, uplink transmissions by said wireless device in said first carrier group employing a first synchronization signal transmitted on said first carrier as a first timing reference; and (2) said second carrier group comprising a second subset of said at least one second carrier; and iii) configuration of transmissions of sounding reference signals on said second carrier in said second carrier group; b) receiving, by said wireless device, an activation command to activate said second carrier in said wireless device; c) receiving, by said wireless device, a control command configured to cause transmission of a random access preamble on random access resources of one of said at least one second carrier in said second subset; d) receiving, by said wireless device, a random access response, said random access response comprising a long time alignment value for said second carrier group and a preamble identifier; and e) transmitting, by said wireless device, one or more of said sounding reference signals on said second carrier after adjusting uplink transmission timing of said second carrier group based on said long time alignment value, said wireless device configured to not transmit any of said sounding reference signals on said second carrier until said wireless device receives said random access response comprising said long time alignment value and an uplink grant.