Patent ID: 8565142

Claim:
A method comprising: a) receiving by a wireless device at least one message causing: i) assignment of each of a plurality of secondary cells in a plurality of cells to one of a plurality of cell groups comprising: (1) a primary cell group comprising a first subset of said plurality of cells; and (2) a secondary cell group comprising a second subset of said plurality of secondary cells; and ii) configuration of random access resources for at least one secondary cell in said plurality of secondary cells; and b) receiving by said wireless device a control command being: i) configurable to cause transmission of a first random access preamble on a secondary cell in said secondary cell group; and ii) unconfigurable to cause transmission of a second random access preamble on any secondary cell in said primary cell group such that any secondary cell in said primary cell group does not include usable random access resources for said wireless device; and c) receiving on a primary cell a random access response comprising a timing advance command configured to cause substantial alignment of reception timing of uplink signals in frames and subframes of said secondary cell group at a base station.