Patent ID: 8462610

Claim:
A method comprising: a) transmitting, by a base station configured to communicate employing a plurality of carriers, at least one radio resource control message to a wireless device in a plurality of wireless devices, said at least one radio resource control message: i) configured to cause in said wireless device: (1) configuration of at least one second carrier in said plurality of carriers; and (2) assignment of each of said at least one second carrier to a carrier group in a plurality of carrier groups, said plurality of carrier groups comprising: (a) a first carrier group comprising a first subset of said plurality of carriers, said first subset comprising a first carrier, uplink transmissions by said wireless device in said first carrier group employing a first synchronization signal transmitted on said first carrier; and (b) at least one second carrier group, a second carrier group in said at least one second carrier group comprising a second subset of said at least one second carrier, said second subset comprising a reference second carrier, uplink transmissions in said second carrier group employing a second synchronization signal on said reference second carrier as a second timing reference; and ii) comprising a plurality of parameters specific to said wireless device, for each of said at least one second carrier: (1) if said plurality of parameters comprise a carrier group index for said second carrier, assigning said second carrier to one of said at least one second carrier group identified by said carrier group index; and (2) otherwise, assigning said second carrier to said first carrier group; b) transmitting, by said base station, a control command configured to cause transmission of a random access preamble on random access resources of a second carrier in said second carrier group; and c) transmitting, by said base station, a random access response on said first carrier, said random access response comprising a timing alignment command for said second carrier group.